feat: Add IP-based rate limiting to login endpoint (#13469)

* feat(security): add failed login logging with IP tracking and comprehensive tests

* fix: remove PII from login logs and fix structlog format

* docs: agent improvements (#13269)

* docs: add structured output for agents

* docs: add structured output note

* docs: clarify both agent outputs and add release notes

* docs: when langflow sends events to the playground and chat history

* fix(playground): expand session checkbox click target to full row height (#13349)

* fix(playground): expand session checkbox click target to full row height

The selectable-row checkbox wrapper was ``w-4 h-4`` (16x16 px) but the
row is ``h-8`` (32 px). The 8 px band above and the 8 px band below
the visible icon were dead zones that bubbled to the row's
``toggleVisibility`` and navigated to the session instead of toggling
selection — exactly the accidental-navigation UX the bug ticket
describes.

Grow the wrapper to ``w-4 h-8`` so the click target captures the full
row height. Width stays narrow so the text alignment is unchanged; the
icon itself stays ``h-4 w-4``, centered via the existing
``flex items-center justify-center``. Visual position is identical.

Adds ``__tests__/session-selector-checkbox-click-target.test.tsx``
(3 cases): wrapper className guard (h-8 + w-4, not h-4), click on the
wrapper outside the icon triggers selection without bubbling to
toggleVisibility, and click on the inner icon still toggles selection.

* test(playground): drop checkbox-click-target test file (not needed per review)

* [autofix.ci] apply automated fixes

* test: align session-selector checkbox assertions with full-height click target

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

* fix: improve trace search functionality (#13383)

* improve trace search functionality

* [autofix.ci] apply automated fixes

---------

Co-authored-by: Olayinka Adelakun <olayinkaadelakun@Olayinkas-MacBook-Pro.local>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

* test: fix test_login_logs_real_output_format to use mocking

- Updated test to use patch() instead of capsys for consistency
- Verifies structlog kwargs format (not nested extra dict)
- All 7 login logging tests now passing

* feat: Add IP-based rate limiting to login endpoint

- Add slowapi dependency for rate limiting functionality
- Implement rate limiting service with configurable limits
- Apply rate limiter to /login endpoint (default: 5 attempts/minute per IP)
- Add custom exception handler for rate limit exceeded (HTTP 429)
- Support both in-memory (default) and Redis storage backends
- Add comprehensive test suite with 100% coverage
- Document configuration in .env.example

Security improvements:
- Prevents brute force attacks on login endpoint
- Structured logging without PII (logs client_ip, not user data)
- Graceful degradation with swallow_errors=True
- Proper X-Forwarded-For header handling for proxied requests

Configuration:
- LANGFLOW_RATE_LIMIT_PER_MINUTE: requests per minute (default: 5)
- LANGFLOW_RATE_LIMIT_STORAGE: storage backend (default: memory://)
- LANGFLOW_RATE_LIMIT_HEADERS_ENABLED: enable rate limit headers (default: false)

* security: add proxy-aware IP extraction for rate limiting

- Add LANGFLOW_RATE_LIMIT_TRUST_PROXY configuration
- Default to secure get_remote_address (prevents header spoofing)
- Enable get_client_ip when behind trusted proxies
- Add comprehensive tests for both configurations
- Maintain 100% test coverage (15 tests passing)

* refactor(rate-limit): address PR review feedback - migrate to Settings model, fix IP security, add test coverage

* fix: disable rate limiting in tests to prevent 429 errors

- Add LANGFLOW_RATE_LIMIT_ENABLED environment variable control
- Disable rate limiting by default in tests via session-scoped fixture
- Rate limit tests explicitly enable it via function-scoped fixture
- Fixes test failures caused by sequential login attempts hitting 5/min limit

* fix: refactor login rate limiting to avoid settings initialization race condition

---------

Co-authored-by: Janardan S Kavia <janardanskavia@Janardans-MacBook-Pro.local>
Co-authored-by: Mendon Kissling <59585235+mendonk@users.noreply.github.com>
Co-authored-by: keval shah <kevalvirat@gmail.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: olayinkaadelakun <olayinka.adelakun@ibm.com>
Co-authored-by: Olayinka Adelakun <olayinkaadelakun@Olayinkas-MacBook-Pro.local>

.env.example

@@ -25,18 +25,17 @@ LANGFLOW_DATABASE_URL=sqlite:///./langflow.db
 # Alembic logs path flag. If set to true, Alembic will log to stdout.
 LANGFLOW_ALEMBIC_LOG_TO_STDOUT=False
 
-
-# mem0 creates a directory 
+# mem0 creates a directory
 # for chat history, vector stores, and other artifacts
 # its default path is ~/.mem0.
-# we can change this path with 
+# we can change this path with
 # environment variable "MEM0_DIR"
 # Example: MEM0_DIR=/tmp/.mem0
 
-# composio creates a cache directory 
+# composio creates a cache directory
 # for file uploads/downloads.
 # its default path is ~/.composio
-# we can change this path with 
+# we can change this path with
 # environment variable "COMPOSIO_CACHE_DIR"
 # Example: COMPOSIO_CACHE_DIR=/tmp/.composio
 
@@ -131,6 +130,28 @@ LANGFLOW_API_KEY_SOURCE=
 # Example: LANGFLOW_API_KEY=your-secure-api-key
 LANGFLOW_API_KEY=
 
+# Rate Limiting Configuration
+# Controls rate limiting for login endpoint to prevent brute force attacks
+# LANGFLOW_RATE_LIMIT_PER_MINUTE: Number of login attempts allowed per minute per IP
+# Values: positive integer (default: 5)
+# Example: LANGFLOW_RATE_LIMIT_PER_MINUTE=10
+LANGFLOW_RATE_LIMIT_PER_MINUTE=
+
+# LANGFLOW_RATE_LIMIT_STORAGE_URI: Storage backend for rate limit counters
+# Values: memory:// (default, single server) or redis://host:port (production, multiple servers)
+# - memory://: Fast, in-memory storage (not shared between server instances, lost on restart)
+# - redis://localhost:6379: Persistent, shared storage (required for load-balanced deployments)
+# Example: LANGFLOW_RATE_LIMIT_STORAGE_URI=redis://localhost:6379
+LANGFLOW_RATE_LIMIT_STORAGE_URI=
+
+# LANGFLOW_RATE_LIMIT_TRUST_PROXY: Trust X-Forwarded-For header for client IP
+# Values: true, false (default: false)
+# When true, uses rightmost X-Forwarded-For IP (the trusted proxy before us)
+# When false, uses direct connection IP (prevents header spoofing in non-proxy deployments)
+# SECURITY: Only enable if behind a trusted proxy (nginx, load balancer, etc.)
+# Example: LANGFLOW_RATE_LIMIT_TRUST_PROXY=true
+LANGFLOW_RATE_LIMIT_TRUST_PROXY=
+
 # Should store environment variables in the database
 # Values: true, false
 LANGFLOW_STORE_ENVIRONMENT_VARIABLES=

.secrets.baseline

@@ -2837,7 +2837,7 @@
         "filename": "src/backend/tests/conftest.py",
         "hashed_secret": "8bb6118f8fd6935ad0876a3be34a717d32708ffd",
         "is_verified": false,
-        "line_number": 480,
+        "line_number": 489,
         "is_secret": false
       },
       {
@@ -2845,7 +2845,7 @@
         "filename": "src/backend/tests/conftest.py",
         "hashed_secret": "61fbb5a12cd7b1f1fe1624120089efc0cd299e43",
         "is_verified": false,
-        "line_number": 690,
+        "line_number": 699,
         "is_secret": false
       }
     ],
@@ -9287,5 +9287,5 @@
       }
     ]
   },
-  "generated_at": "2026-06-02T14:40:31Z"
+  "generated_at": "2026-06-03T21:32:15Z"
 }

src/backend/base/langflow/api/v1/login.py

@@ -4,7 +4,10 @@ from typing import Annotated
 
 from fastapi import APIRouter, Depends, HTTPException, Request, Response, status
 from fastapi.security import OAuth2PasswordRequestForm
+from limits import parse
 from pydantic import BaseModel
+from slowapi.errors import RateLimitExceeded
+from slowapi.wrappers import Limit
 
 from langflow.api.utils import DbSession
 from langflow.api.v1.schemas import Token
@@ -12,10 +15,45 @@ from langflow.initial_setup.setup import get_or_create_default_folder
 from langflow.services.database.models.user.crud import get_user_by_id
 from langflow.services.database.models.user.model import UserRead
 from langflow.services.deps import get_auth_service, get_settings_service, get_variable_service
+from langflow.services.rate_limit import get_rate_limit_string
 
 router = APIRouter(tags=["Login"])
 
 
+def get_limiter_from_app(request: Request):
+    """Get the rate limiter from app state (initialized after settings load)."""
+    return request.app.state.limiter
+
+
+def check_rate_limit(request: Request) -> None:
+    """Check and enforce rate limit for the request.
+
+    Retrieves the limiter from app.state (initialized after settings load in main.py)
+    and manually checks the rate limit using the limits library.
+
+    Raises:
+        RateLimitExceeded: If the rate limit is exceeded
+    """
+    limiter = get_limiter_from_app(request)
+
+    # Parse the rate limit string and check if limit is exceeded
+    limit_item = parse(get_rate_limit_string())
+    if not limiter._limiter.hit(limit_item, limiter._key_func(request)):  # noqa: SLF001
+        # Limit exceeded - raise RateLimitExceeded with proper wrapper
+        limit_wrapper = Limit(
+            limit=limit_item,
+            key_func=limiter._key_func,  # noqa: SLF001
+            scope=None,
+            per_method=False,
+            methods=None,
+            error_message=None,
+            exempt_when=None,
+            cost=1,
+            override_defaults=False,
+        )
+        raise RateLimitExceeded(limit_wrapper)
+
+
 class SessionResponse(BaseModel):
     """Session validation response."""
 
@@ -31,6 +69,10 @@ async def login_to_get_access_token(
     form_data: Annotated[OAuth2PasswordRequestForm, Depends()],
     db: DbSession,
 ):
+    """Login endpoint with rate limiting applied via app.state.limiter."""
+    # Check rate limit (limiter is initialized in main.py after settings load)
+    check_rate_limit(request)
+
     auth_settings = get_settings_service().auth_settings
     try:
         auth = get_auth_service()

src/backend/base/langflow/main.py

@@ -757,6 +757,36 @@ def create_app():
             content={"detail": exc.detail},
         )
 
+    # Add rate limit exception handler
+    from slowapi.errors import RateLimitExceeded
+
+    @app.exception_handler(RateLimitExceeded)
+    async def rate_limit_exception_handler(request: Request, _exc: RateLimitExceeded):
+        """Handle rate limit exceeded errors with structured logging."""
+        from langflow.services.rate_limit.service import get_limiter_key
+
+        # Default to 60 seconds for "/minute" window
+        retry_after_seconds = "60"
+
+        client_ip = get_limiter_key(request)
+        logger.warning(
+            "Rate limit exceeded",
+            auth_event="rate_limit_exceeded",
+            client_ip=client_ip,
+            path=request.url.path,
+            method=request.method,
+        )
+        return JSONResponse(
+            status_code=HTTPStatus.TOO_MANY_REQUESTS,
+            content={
+                "detail": "Too many requests. Please try again later.",
+                "retry_after": retry_after_seconds,
+            },
+            headers={
+                "Retry-After": retry_after_seconds,
+            },
+        )
+
     @app.exception_handler(Exception)
     async def exception_handler(_request: Request, exc: Exception):
         if isinstance(exc, HTTPException):
@@ -778,6 +808,12 @@ def create_app():
 
     add_pagination(app)
 
+    # Add SlowAPI state to app for rate limiting
+    from langflow.services.rate_limit import get_rate_limiter
+
+    limiter = get_rate_limiter()
+    app.state.limiter = limiter
+
     return app
 
 

src/backend/base/langflow/services/rate_limit/__init__.py

@@ -0,0 +1,12 @@
+"""Rate limiting service for Langflow API endpoints.
+
+This module provides rate limiting functionality using SlowAPI to protect
+against brute force attacks and abuse. It supports both IP-based and custom
+key-based rate limiting with configurable storage backends.
+"""
+
+from __future__ import annotations
+
+from langflow.services.rate_limit.service import get_limiter_key, get_rate_limit_string, get_rate_limiter
+
+__all__ = ["get_limiter_key", "get_rate_limit_string", "get_rate_limiter"]

src/backend/base/langflow/services/rate_limit/service.py

@@ -0,0 +1,104 @@
+"""Rate limiting service implementation.
+
+Provides a configured SlowAPI Limiter instance for rate limiting endpoints.
+Uses in-memory storage by default, with support for Redis in production.
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from slowapi import Limiter
+from slowapi.util import get_remote_address
+
+from langflow.services.deps import get_settings_service
+
+if TYPE_CHECKING:
+    from fastapi import Request
+
+# Global limiter instance
+_limiter: Limiter | None = None
+
+
+def get_rate_limit_string() -> str:
+    """Get the rate limit string from settings.
+
+    Returns:
+        str: Rate limit string in format "N/minute", or a very high limit if disabled
+    """
+    settings = get_settings_service().settings
+    if not settings.rate_limit_enabled:
+        # Return a very high limit to effectively disable rate limiting
+        return "10000/minute"
+    return f"{settings.rate_limit_per_minute}/minute"
+
+
+def get_rate_limiter() -> Limiter:
+    """Get or create the global rate limiter instance.
+
+    Returns:
+        Limiter: Configured SlowAPI Limiter instance
+    """
+    global _limiter  # noqa: PLW0603
+
+    if _limiter is None:
+        settings = get_settings_service().settings
+
+        # Choose key function based on proxy configuration
+        # When behind trusted proxies (load balancer, reverse proxy), use X-Forwarded-For
+        # Otherwise use direct connection IP to prevent header spoofing
+        key_func = get_client_ip if settings.rate_limit_trust_proxy else get_remote_address
+
+        _limiter = Limiter(
+            key_func=key_func,
+            storage_uri=settings.rate_limit_storage_uri,
+            # Don't swallow errors - we want rate limit violations to raise exceptions
+            swallow_errors=False,
+        )
+
+    return _limiter
+
+
+def get_client_ip(request: Request) -> str:
+    """Extract client IP address from request, using rightmost X-Forwarded-For entry.
+
+    When behind a trusted proxy, the rightmost IP in X-Forwarded-For is the last hop
+    before our server (the trusted proxy itself). The leftmost IP is client-supplied
+    and can be spoofed.
+
+    Args:
+        request: FastAPI Request object
+
+    Returns:
+        str: Client IP address
+    """
+    # Check X-Forwarded-For header first (for proxied requests)
+    forwarded_for = request.headers.get("X-Forwarded-For")
+    if forwarded_for:
+        # X-Forwarded-For format: "client, proxy1, proxy2"
+        # Take the rightmost IP (last proxy before us)
+        ips = [ip.strip() for ip in forwarded_for.split(",")]
+        return ips[-1]
+
+    # Fall back to direct client IP
+    if request.client:
+        return request.client.host
+
+    return "unknown"
+
+
+def get_limiter_key(request: Request) -> str:
+    """Get the key that the limiter will actually use for this request.
+
+    This matches the limiter's key_func to ensure logging uses the same IP.
+
+    Args:
+        request: FastAPI Request object
+
+    Returns:
+        str: The IP address or key used for rate limiting
+    """
+    settings = get_settings_service().settings
+    if settings.rate_limit_trust_proxy:
+        return get_client_ip(request)
+    return get_remote_address(request)

src/backend/base/pyproject.toml

@@ -19,6 +19,7 @@ maintainers = [
 dependencies = [
     "lfx~=0.5.0",
     "fastapi>=0.135.0,<1.0.0",
+    "slowapi>=0.1.9,<1.0.0",
     "httpx[http2]>=0.27,<1.0.0",
     "aiofile>=3.9.0,<4.0.0",
     "uvicorn>=0.30.0,<1.0.0",

src/backend/tests/conftest.py

@@ -1,5 +1,6 @@
 import asyncio
 import json
+import os
 import shutil
 
 # we need to import tmpdir
@@ -41,6 +42,14 @@ from tests.api_keys import get_openai_api_key
 load_dotenv()
 
 
+@pytest.fixture(scope="session", autouse=True)
+def disable_rate_limiting():
+    """Disable rate limiting for all tests to prevent 429 errors during test execution."""
+    os.environ["LANGFLOW_RATE_LIMIT_ENABLED"] = "false"
+    yield
+    os.environ.pop("LANGFLOW_RATE_LIMIT_ENABLED", None)
+
+
 # TODO: Revert this to True once bb.functions[func].can_block_in("http/client.py", "_safe_read") is fixed
 @pytest.fixture(autouse=False)
 def blockbuster(request):

src/backend/tests/unit/test_login_rate_limiting.py

@@ -0,0 +1,244 @@
+"""Tests for login endpoint rate limiting functionality."""
+
+from __future__ import annotations
+
+from unittest.mock import Mock
+
+import pytest
+
+
+@pytest.fixture
+def enable_rate_limiting(monkeypatch):
+    """Enable rate limiting for tests that need to verify rate limit behavior."""
+    monkeypatch.setenv("LANGFLOW_RATE_LIMIT_ENABLED", "true")
+
+
+@pytest.fixture
+def limiter_snapshot():
+    """Fixture to snapshot and restore the global limiter singleton."""
+    import langflow.services.rate_limit.service as rate_limit_module
+
+    original_limiter = rate_limit_module._limiter
+    # Force recreation of limiter for each test to ensure clean state
+    rate_limit_module._limiter = None
+    yield
+    rate_limit_module._limiter = original_limiter
+
+
+class TestRateLimitService:
+    """Test suite for rate limit service configuration."""
+
+    def test_rate_limiter_is_configured(self, enable_rate_limiting):  # noqa: ARG002
+        """Test that rate limiter singleton is properly configured."""
+        from langflow.services.rate_limit import get_rate_limiter
+
+        limiter = get_rate_limiter()
+
+        assert limiter is not None
+        assert limiter.enabled is True
+        assert limiter._storage_uri == "memory://"  # Default storage
+        assert limiter._swallow_errors is False  # Raise exceptions on rate limit
+
+    def test_rate_limiter_is_singleton(self, enable_rate_limiting):  # noqa: ARG002
+        """Test that get_rate_limiter returns the same instance."""
+        from langflow.services.rate_limit import get_rate_limiter
+
+        limiter1 = get_rate_limiter()
+        limiter2 = get_rate_limiter()
+
+        assert limiter1 is limiter2
+
+    def test_rate_limit_string_default(self, enable_rate_limiting):  # noqa: ARG002
+        """Test that default rate limit string is correct."""
+        from langflow.services.rate_limit.service import get_rate_limit_string
+
+        rate_limit = get_rate_limit_string()
+
+        assert rate_limit == "5/minute"
+
+    def test_rate_limiter_uses_remote_address_by_default(self, enable_rate_limiting):  # noqa: ARG002
+        """Test that rate limiter uses get_remote_address when trust_proxy is false."""
+        from langflow.services.rate_limit import get_rate_limiter
+        from slowapi.util import get_remote_address
+
+        limiter = get_rate_limiter()
+
+        # Default should use get_remote_address (not trust proxy)
+        assert limiter._key_func == get_remote_address
+
+    def test_rate_limiter_uses_client_ip_when_trust_proxy_enabled(
+        self,
+        enable_rate_limiting,  # noqa: ARG002
+        limiter_snapshot,  # noqa: ARG002
+        monkeypatch,
+    ):
+        """Test that rate limiter uses get_client_ip when trust_proxy is true."""
+        # Mock settings to enable trust_proxy
+        from unittest.mock import MagicMock
+
+        from langflow.services.rate_limit.service import get_client_ip
+
+        mock_settings = MagicMock()
+        mock_settings.rate_limit_trust_proxy = True
+        mock_settings.rate_limit_storage_uri = "memory://"
+
+        mock_settings_service = MagicMock()
+        mock_settings_service.settings = mock_settings
+
+        monkeypatch.setattr("langflow.services.rate_limit.service.get_settings_service", lambda: mock_settings_service)
+
+        from langflow.services.rate_limit import get_rate_limiter
+
+        limiter = get_rate_limiter()
+
+        # Should use get_client_ip when trust_proxy is enabled
+        assert limiter._key_func == get_client_ip
+
+
+class TestIPExtraction:
+    """Test suite for IP address extraction logic."""
+
+    def test_get_client_ip_from_x_forwarded_for_single(self):
+        """Test IP extraction from X-Forwarded-For with single IP."""
+        from langflow.services.rate_limit.service import get_client_ip
+
+        request = Mock()
+        request.headers = {"X-Forwarded-For": "203.0.113.1"}
+        request.client = Mock(host="127.0.0.1")
+
+        ip = get_client_ip(request)
+
+        assert ip == "203.0.113.1"
+
+    def test_get_client_ip_from_x_forwarded_for_chain_uses_rightmost(self):
+        """Test IP extraction from X-Forwarded-For uses rightmost IP (trusted proxy)."""
+        from langflow.services.rate_limit.service import get_client_ip
+
+        request = Mock()
+        request.headers = {"X-Forwarded-For": "203.0.113.1, 198.51.100.1, 192.0.2.1"}
+        request.client = Mock(host="127.0.0.1")
+
+        ip = get_client_ip(request)
+
+        # Should use rightmost IP (the trusted proxy before us)
+        assert ip == "192.0.2.1"
+
+    def test_get_client_ip_from_x_forwarded_for_with_spaces(self):
+        """Test IP extraction handles spaces in X-Forwarded-For."""
+        from langflow.services.rate_limit.service import get_client_ip
+
+        request = Mock()
+        request.headers = {"X-Forwarded-For": "  203.0.113.1  ,  198.51.100.1  "}
+        request.client = Mock(host="127.0.0.1")
+
+        ip = get_client_ip(request)
+
+        # Should use rightmost IP, stripped of whitespace
+        assert ip == "198.51.100.1"
+
+    def test_get_client_ip_from_direct_connection(self):
+        """Test IP extraction from direct client connection (no proxy)."""
+        from langflow.services.rate_limit.service import get_client_ip
+
+        request = Mock()
+        request.headers = {}
+        request.client = Mock(host="192.168.1.100")
+
+        ip = get_client_ip(request)
+
+        assert ip == "192.168.1.100"
+
+    def test_get_client_ip_fallback_to_unknown(self):
+        """Test IP extraction returns 'unknown' when no client info available."""
+        from langflow.services.rate_limit.service import get_client_ip
+
+        request = Mock()
+        request.headers = {}
+        request.client = None
+
+        ip = get_client_ip(request)
+
+        assert ip == "unknown"
+
+    def test_get_client_ip_prefers_x_forwarded_for(self):
+        """Test that X-Forwarded-For takes precedence over direct client IP."""
+        from langflow.services.rate_limit.service import get_client_ip
+
+        request = Mock()
+        request.headers = {"X-Forwarded-For": "203.0.113.1"}
+        request.client = Mock(host="127.0.0.1")
+
+        ip = get_client_ip(request)
+
+        # Should use X-Forwarded-For, not client.host
+        assert ip == "203.0.113.1"
+        assert ip != "127.0.0.1"
+
+
+class TestRateLimitIntegration:
+    """Integration tests verifying rate limiting is applied to login endpoint."""
+
+    def test_rate_limit_enforcement_returns_429(self, enable_rate_limiting, limiter_snapshot, active_user):  # noqa: ARG002
+        """Test that exceeding rate limit returns 429 status code.
+
+        Uses TestClient (synchronous) instead of AsyncClient to properly test SlowAPI rate limiting.
+        Requires limiter_snapshot fixture to ensure clean state and avoid interference from other tests.
+        """
+        from fastapi.testclient import TestClient
+        from langflow.main import create_app
+
+        # Create a fresh app instance for this test
+        app = create_app()
+        sync_client = TestClient(app)
+
+        # Make 5 requests (the default limit)
+        status_codes = []
+        for i in range(5):
+            response = sync_client.post(
+                "/api/v1/login",
+                data={"username": active_user.username, "password": "testpassword"},  # pragma: allowlist secret
+            )
+            status_codes.append(response.status_code)
+            assert response.status_code == 200, f"Request {i + 1} should succeed, got {response.status_code}"
+
+        # 6th request should be rate limited
+        response = sync_client.post(
+            "/api/v1/login",
+            data={"username": active_user.username, "password": "testpassword"},  # pragma: allowlist secret
+        )
+        status_codes.append(response.status_code)
+
+        assert response.status_code == 429, f"Expected 429, got {response.status_code}. All codes: {status_codes}"
+        response_detail = response.json()["detail"].lower()
+        assert "too many requests" in response_detail or "rate limit" in response_detail
+
+    @pytest.mark.asyncio
+    async def test_login_endpoint_has_rate_limiter_applied(self, enable_rate_limiting):  # noqa: ARG002
+        """Test that the login endpoint has rate limiting applied via app.state.limiter."""
+        from langflow.api.v1.login import get_limiter_from_app, login_to_get_access_token
+        from langflow.main import create_app
+
+        # Create app to ensure limiter is attached to app.state
+        app = create_app()
+
+        # Verify limiter is attached to app.state
+        assert hasattr(app.state, "limiter")
+        assert app.state.limiter is not None
+        assert app.state.limiter.enabled is True
+
+        # Verify the endpoint function exists
+        assert login_to_get_access_token is not None
+        # Verify get_limiter_from_app helper exists
+        assert get_limiter_from_app is not None
+
+    @pytest.mark.asyncio
+    async def test_successful_login_within_reasonable_limit(self, enable_rate_limiting, client, active_user):  # noqa: ARG002
+        """Test that a single login request succeeds (well within any rate limit)."""
+        response = await client.post(
+            "/api/v1/login",
+            data={"username": active_user.username, "password": "testpassword"},  # pragma: allowlist secret
+            headers={"X-Forwarded-For": "10.0.0.1"},  # Unique IP to avoid conflicts
+        )
+
+        assert response.status_code == 200
+        assert "access_token" in response.json()

src/lfx/src/lfx/services/settings/base.py

@@ -255,6 +255,16 @@ class Settings(BaseSettings):
     redis_url: str | None = None
     redis_cache_expire: int = 3600
 
+    # Rate Limiting
+    rate_limit_enabled: bool = True
+    """Enable rate limiting for login endpoint. Set to False to disable (useful for testing)."""
+    rate_limit_per_minute: int = 5
+    """Number of login attempts allowed per minute per IP."""
+    rate_limit_storage_uri: str = "memory://"
+    """Storage backend for rate limiting. Use 'memory://' for single-server or 'redis://host:port' for multi-server."""
+    rate_limit_trust_proxy: bool = False
+    """Trust X-Forwarded-For header when behind a reverse proxy. Only enable when behind a trusted proxy."""
+
     # Job Queue
     job_queue_type: Literal["asyncio", "redis"] = "asyncio"
     """The job queue backend. Use 'redis' for multi-worker deployments to solve cross-worker JobQueueNotFoundError."""

uv.lock

@@ -7675,6 +7675,7 @@ dependencies = [
     { name = "scipy", version = "1.17.1", source = { registry = "https://pypi.org/simple" }, marker = "python_full_version >= '3.11'" },
     { name = "sentry-sdk", extra = ["fastapi", "loguru"] },
     { name = "setuptools" },
+    { name = "slowapi" },
     { name = "spider-client" },
     { name = "sqlalchemy", extra = ["aiosqlite"] },
     { name = "sqlmodel" },
@@ -8595,6 +8596,7 @@ requires-dist = [
     { name = "sentence-transformers", marker = "extra == 'sentence-transformers'", specifier = ">=2.3.1" },
     { name = "sentry-sdk", extras = ["fastapi", "loguru"], specifier = ">=2.5.1,<3.0.0" },
     { name = "setuptools", specifier = ">=80.0.0,<81.0.0" },
+    { name = "slowapi", specifier = ">=0.1.9,<1.0.0" },
     { name = "smolagents", marker = "extra == 'smolagents'", specifier = ">=1.8.0" },
     { name = "spider-client", specifier = ">=0.0.27,<1.0.0" },
     { name = "spider-client", marker = "extra == 'spider'", specifier = ">=0.0.27,<1.0.0" },
@@ -9345,6 +9347,20 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/ce/62/b40b382fa0c66fee1478073eb8db352a4a6beda4a1adccf1df911d8c289c/librt-0.11.0-cp314-cp314t-win_arm64.whl", hash = "sha256:dee008f20b542e3cd162ba338a7f9ec0f6d23d395f66fe8aeeec3c9d067ea253", size = 102572, upload-time = "2026-05-10T18:17:06.809Z" },
 ]
 
+[[package]]
+name = "limits"
+version = "5.8.0"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "deprecated" },
+    { name = "packaging" },
+    { name = "typing-extensions" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/71/69/826a5d1f45426c68d8f6539f8d275c0e4fcaa57f0c017ec3100986558a41/limits-5.8.0.tar.gz", hash = "sha256:c9e0d74aed837e8f6f50d1fcebcf5fd8130957287206bc3799adaee5092655da", size = 226104, upload-time = "2026-02-05T07:17:35.859Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/b9/98/cb5ca20618d205a09d5bec7591fbc4130369c7e6308d9a676a28ff3ab22c/limits-5.8.0-py3-none-any.whl", hash = "sha256:ae1b008a43eb43073c3c579398bd4eb4c795de60952532dc24720ab45e1ac6b8", size = 60954, upload-time = "2026-02-05T07:17:34.425Z" },
+]
+
 [[package]]
 name = "line-profiler"
 version = "5.0.2"
@@ -17127,6 +17143,18 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/b7/ce/149a00dd41f10bc29e5921b496af8b574d8413afcd5e30dfa0ed46c2cc5e/six-1.17.0-py2.py3-none-any.whl", hash = "sha256:4721f391ed90541fddacab5acf947aa0d3dc7d27b2e1e8eda2be8970586c3274", size = 11050, upload-time = "2024-12-04T17:35:26.475Z" },
 ]
 
+[[package]]
+name = "slowapi"
+version = "0.1.9"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "limits" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/a0/99/adfc7f94ca024736f061257d39118e1542bade7a52e86415a4c4ae92d8ff/slowapi-0.1.9.tar.gz", hash = "sha256:639192d0f1ca01b1c6d95bf6c71d794c3a9ee189855337b4821f7f457dddad77", size = 14028, upload-time = "2024-02-05T12:11:52.13Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/2b/bb/f71c4b7d7e7eb3fc1e8c0458a8979b912f40b58002b9fbf37729b8cb464b/slowapi-0.1.9-py3-none-any.whl", hash = "sha256:cfad116cfb84ad9d763ee155c1e5c5cbf00b0d47399a769b227865f5df576e36", size = 14670, upload-time = "2024-02-05T12:11:50.898Z" },
+]
+
 [[package]]
 name = "smmap"
 version = "5.0.3"