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

Patched release: v1.84.0

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

github.com

https://github.com/BerriAI/litellm/security/advisories/GHSA-4xpc-pv4p-pm3w

github.com

https://github.com/BerriAI/litellm/releases/tag/v1.84.0

github.com

https://github.com/advisories/GHSA-4xpc-pv4p-pm3w

JSON source

https://cveawg.mitre.org/api/cve/CVE-2026-49468

Click to expand

{
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "cveMetadata": {
    "cveId": "CVE-2026-49468",
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "dateUpdated": "2026-06-22T20:37:14.494Z",
    "dateReserved": "2026-05-30T04:17:43.094Z",
    "datePublished": "2026-06-22T20:37:14.494Z",
    "state": "PUBLISHED"
  },
  "containers": {
    "cna": {
      "providerMetadata": {
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M",
        "dateUpdated": "2026-06-22T20:37:14.494Z"
      },
      "title": "LiteLLM: Authentication Bypass via Host Header Injection",
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "affected": [
        {
          "vendor": "BerriAI",
          "product": "litellm",
          "versions": [
            {
              "version": "< 1.84.0",
              "status": "affected"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "CWE-290: Authentication Bypass by Spoofing",
              "cweId": "CWE-290",
              "type": "CWE"
            }
          ]
        }
      ],
      "references": [
        {
          "url": "https://github.com/BerriAI/litellm/security/advisories/GHSA-4xpc-pv4p-pm3w",
          "name": "https://github.com/BerriAI/litellm/security/advisories/GHSA-4xpc-pv4p-pm3w",
          "tags": [
            "x_refsource_CONFIRM"
          ]
        },
        {
          "url": "https://github.com/BerriAI/litellm/releases/tag/v1.84.0",
          "name": "https://github.com/BerriAI/litellm/releases/tag/v1.84.0",
          "tags": [
            "x_refsource_MISC"
          ]
        }
      ],
      "metrics": [
        {}
      ]
    }
  }
}