CVE-2026-59822
LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback
At a glance
- Source
- NVD
- EPSS
- EPSS 0.84 % · percentile 58 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
Description
LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.84.0, LiteLLM's MCP Streamable HTTP endpoint allowed an unauthenticated attacker to use a fabricated Authorization header to trigger an OAuth2 passthrough fallback path that replaced failed LiteLLM key validation with an empty UserAPIKeyAuth() object, allowing requests to reach MCP tooling without a valid LiteLLM key. This issue is fixed in version 1.84.0.
Weaknesses (CWE)
References
- https://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95q
- https://github.com/BerriAI/litellm/pull/26463
- https://github.com/BerriAI/litellm/commit/73869f0faf7d11ee21adcb5f91b8c33a340b6c2c
- https://github.com/BerriAI/litellm/releases/tag/v1.84.0
- https://www.wiz.io/blog/ai-infrastructure-honeypot
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-59822
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | HIGH 8.8 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N | GitHub_M |
| CVSS 4.0 | HIGH 8.8 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD · security-advisories@github.com (Secondary) |
| CVSS 3.1 | HIGH 8.2 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N | NVD · nvd@nist.gov (Primary) |
Advisories
- GHSA-7488-6r32-c95q — LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback
- PYSEC-2026-3479 — LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback
European references
- ENISA EUVD · EUVD-2026-42359
- GCVE · GCVE-0-2026-59822
Affected configurations (NVD CPE)
cpe:2.3:a:litellm:litellm:*:*:*:*:*:*:*:*< 1.84.0
Affected products
| Product | Versions |
|---|---|
| BerriAI · litellm | affected < 1.84.0 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| CISA Known Exploited Vulnerabilities | CC0 1.0 |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |