Vulnerability details
CVE-2026-59822
Actively exploited
BerriAI litellm
LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback
CVSS 4.0
8.8High
Official 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.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 8.8High | 4.0 | CVEProject cvelistV5 (CNA) (GitHub_M) | 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 |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| BerriAI | litellm | < 1.84.0 | CVEProject cvelistV5 (CNA) |
References and advisories
6- https://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95q x_refsource_CONFIRM
- https://github.com/BerriAI/litellm/pull/26463 x_refsource_MISC
- https://github.com/BerriAI/litellm/commit/73869f0faf7d11ee21adcb5f91b8c33a340b6c2c x_refsource_MISC
- https://github.com/BerriAI/litellm/releases/tag/v1.84.0 x_refsource_MISC
- https://www.wiz.io/blog/ai-infrastructure-honeypot third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-59822 government-resource
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Details
- Published
- 2026-07-08
- Last updated
- 2026-09-03
- State
- Published
- Assigner (CNA)
- GitHub_M
- Kolun priority
- 68 · High
CISA KEV catalog
- Date added
- 2026-09-02
- Due date
- 2026-09-16
- Used in ransomware
- Unknown
Exploit prediction (EPSS)
0.83%
Probability of exploitation in 30 days
58%
Percentile (among all CVEs)
SSVC assessment (CISA)
- Automatable
- Yes
- Exploitation
- Active
- Technical impact
- Partial
Weaknesses (CWE)
- CWE-287Improper Authentication
- CWE-306Missing Authentication for Critical Function