LiteLLM: Authentication Bypass via Host Header Injection

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

9.5 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H · score source

EPSS

• CVE-2026-49468: 3.03% estimated exploitation activity in the next 30 days; percentile 87.51 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

16 Jun 2026, 23:38 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:49 UTC

1. Revision 4 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-4xpc-pv4p-pm3w

2. Revision 3 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-4xpc-pv4p-pm3w

4. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-4xpc-pv4p-pm3w

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# Patch Next advisory brief: CVE-2026-49468

Advisory: LiteLLM: Authentication Bypass via Host Header Injection
IDs: CVE-2026-49468, GHSA-4xpc-pv4p-pm3w
Record: https://patchnext.com/advisories/cve-2026-49468 (revision 4, source checked 26 Oct 2026, 13:49 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: litellm 1.84.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI litellm: affected < 1.84.0; fixed in 1.84.0

## Suggested inspection (read-only)
- `python -m pip show litellm`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on litellm.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4xpc-pv4p-pm3w (GitHub-reviewed advisory GHSA-4xpc-pv4p-pm3w lists affected ranges: PyPI litellm >=0 <1.84.0)
- Verified: https://osv.dev/vulnerability/GHSA-4xpc-pv4p-pm3w (OSV record GHSA-4xpc-pv4p-pm3w lists affected ranges: PyPI litellm >=0 <1.84.0 (fixed))

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