CVE-2026-59822
BerriAI LiteLLM Improper Authentication Vulnerability
CVSS
8.2
High
EPSS
0.5%
p42
KEV
YES
Sep 2, 2026
Exploit Today
63
0-100
Published: Jul 8, 2026 · Last modified: Sep 3, 2026 · CWE-287 · CWE-306
Product
BerriAI / LiteLLM
Vulnerability
BerriAI LiteLLM Improper Authentication Vulnerability
Added to KEV
Sep 2, 2026
Remediate by
Sep 16, 2026
Known ransomware use
No
Summary description
BerriAI LiteLLM contains an improper authentication vulnerability in the MCP Streamable HTTP endpoint that could allow an unauthenticated attacker to establish an authenticated MCP session using an arbitrary Bearer token.
Required action
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Notes
https://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95q ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-59822
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.
- github.comhttps://github.com/BerriAI/litellm/commit/73869f0faf7d11ee21adcb5f91b8c33a340b6c2c
- github.comhttps://github.com/BerriAI/litellm/pull/26463
- github.comhttps://github.com/BerriAI/litellm/releases/tag/v1.84.0
- github.comhttps://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95q
- www.cisa.govhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-59822
- www.wiz.iohttps://www.wiz.io/blog/ai-infrastructure-honeypot