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AI agent vulnerability · LiteLLM

CVE-2026-49468: LiteLLM: Authentication Bypass via Host Header Injection

criticalCVSS 4.0 9.5 · 3.1 9.8GHSA-4xpc-pv4p-pm3w

Impact A Host-header parsing flaw in the LiteLLM proxy could, under specific conditions, allow unauthenticated access to protected management routes. The auth layer derived the effective route from request.url.path in litellm/proxy/auth/authutils.py::getrequestroute(), which Starlette reconstructs from the Host header.

Published Jun 16, 2026 · Updated Jul 18, 2026

Affected packages

litellm

Ecosystem
PyPI
Affected
< 1.84.0
Fixed in
1.84.0
Check
pip show litellm

Advisory details

From the GitHub Advisory Database (CC BY 4.0).

Impact

A Host-header parsing flaw in the LiteLLM proxy could, under specific conditions, allow unauthenticated access to protected management routes.

The auth layer derived the effective route from request.url.path in litellm/proxy/auth/auth_utils.py::get_request_route(), which Starlette reconstructs from the Host header. A crafted Host could therefore make the auth gate evaluate a different route from the one FastAPI dispatched.

Most deployments are not affected. The bypass is blocked by any upstream layer that validates or normalizes Host, such as:

  • a CDN or WAF, such as Cloudflare
  • a reverse proxy with server_name allowlists
  • a host-based load balancer

LiteLLM Cloud customers are not affected.

Patches

Fixed in `1.84.0`. Upgrade to 1.84.0 or later. No configuration change is required.

Workarounds

If upgrading is not immediately possible, place the proxy behind an upstream component that validates or normalizes the Host header before forwarding (a CDN/WAF, a reverse proxy with explicit server_name allowlists, or a cloud load balancer with host-based routing rules), or otherwise restrict network access to the proxy listener.

References

Discovery Credit: Le The Thang (KCSC) and Kim Ngoc Chung (One Mount Group)

Credited to LilThawg29.

References

How this page is made: the data panel comes from the GitHub Advisory Database, CISA’s KEV catalog, the NVD and FIRST EPSS, and updates twice a day. No analysis has been written for this entry yet. Methodology

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