CVE-2026-49468: LiteLLM: Authentication Bypass via Host Header Injection
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. 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 servername 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 servername allowlists, or a cloud load balancer with host-based routing rules), or otherwise restrict network access to the proxy listener.
References
- Patched release: v1.84.0
Discovery Credit: Le The Thang (KCSC) and Kim Ngoc Chung (One Mount Group)
Other sources
LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.84.0, This vulnerability is fixed in 1.84.0.
— NVD
LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.84.0, 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. A crafted Host could therefore make the auth gate evaluate a different route from the one FastAPI dispatched. This vulnerability is fixed in 1.84.0.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
pip/litellmto a version that resolves this vulnerability.Fixed in 1.84.0 - Upgrade
Upgrade
LiteLLMto a version that resolves this vulnerability.Fixed in 1.84.0 - Compensating control
If upgrading is not immediately possible, place the LiteLLM proxy behind an upstream component that validates or normalizes the Host header before forwarding (e.g., a CDN/WAF such as Cloudflare, 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.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-49468?
The severity of CVE-2026-49468 is rated at risk level 44.
What kind of vulnerability is CVE-2026-49468?
CVE-2026-49468 is a Host-header parsing flaw that may allow unauthenticated access to protected management routes.
How do I fix CVE-2026-49468?
To fix CVE-2026-49468, update to the latest version of LiteLLM where the vulnerability has been patched.
What impact does CVE-2026-49468 have on my system?
CVE-2026-49468 can lead to unauthorized access to sensitive management routes under specific conditions.
Which software is affected by CVE-2026-49468?
CVE-2026-49468 affects the LiteLLM software package.