CVE-2026-59822KEV · OVERDUECWE-287CWE-306

BerriAI LiteLLM Improper Authentication Vulnerability

High · published July 9, 2026

Patch now

Confirmed exploited, and the score agrees

CVSS calls it high at 8.2. It is confirmed in active exploitation. It sits in the 57.3th percentile for exploit probability.

38
days past CISA
deadline
CVSS v3.1
8.2
EPSS
1%
Percentile
57.3
In the wild
Confirmed
What it is

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.

The record
Technical detail
CVSS v3.1
8.2 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00836 · 57.3th percentile
Weaknesses
CWE-287 · Improper Authentication; CWE-306 · Missing Authentication for Critical Function
Published
2026-07-09T00:16Z
KEV added
2026-09-02 · due 2026-09-16
Affected products (1)
ProductVersionsFixed in
litellm/litellm< 1.84.01.84.0
References (6)
https://github.com/BerriAI/litellm/commit/73869f0faf7d11ee21adcb5f91b8c33a340b6c2c · [email protected]https://github.com/BerriAI/litellm/pull/26463 · [email protected]https://github.com/BerriAI/litellm/releases/tag/v1.84.0 · [email protected]https://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95q · [email protected]https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-59822 · 134c704f-9b21-4f2e-91b3-4a467353bcc0https://www.wiz.io/blog/ai-infrastructure-honeypot · 134c704f-9b21-4f2e-91b3-4a467353bcc0
EPSS history
Timeline
  • 02 SEP 00:00Z
    Added to CISA KEV — remediate by Sep 16
    kev
  • 08 JUL 19:32Z
    LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback
    cvelistv5