Security brief

LiteLLM Host-header authentication bypass depended on upstream request handling

REVIEW

CVE-2026-49468 affected certain proxy deployments; the advisory says LiteLLM Cloud was not affected.

Published 29 Oct 2026 · Material update 16 Jun 2026 — last time the underlying evidence changed · Evidence: high

What happened

A LiteLLM advisory describes a Host-header parsing flaw that could cause its authentication layer to evaluate a different route from the one the application served. Under the relevant conditions, protected management routes could become accessible without authentication.

The advisory says most deployments were not affected: upstream components that validated or normalized Host headers blocked the bypass. It specifically excludes LiteLLM Cloud customers.

Version 1.84.0 fixes the issue. Upgrade to a maintained release and check the actual path through your CDN, load balancer and reverse proxy. If updating is delayed, enforce Host validation upstream and restrict direct access to the proxy listener.

Read the original source.

Next step

Update LiteLLM and enforce valid Host headers before requests reach the proxy.

What we know

Fixed version
1.84.0.
Excluded by advisory
LiteLLM Cloud.

What remains unknown

Open question
The sources reviewed do not establish whether your deployment was exploited.

Source references

Technical details

CVE
CVE-2026-49468