Summary
generated automatically from NVD dataLiteLLM, the proxy server (AI Gateway) for calling LLM APIs, has an authentication bypass (CWE-287) in its MCP Streamable HTTP endpoint before version 1.84.0. An unauthenticated attacker can send a fabricated Authorization header to trigger an OAuth2 passthrough fallback that swaps failed key validation for an empty UserAPIKeyAuth() object, reaching MCP tooling without a valid LiteLLM key. The flaw is rated HIGH with a CVSS v3.1 score of 8.2, is listed in the CISA KEV catalog, and is fixed in 1.84.0.
NVD 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.
⚠️ Actively exploited — CISA KEV
This CVE was added to CISA's Known Exploited Vulnerabilities catalog on 2026-09-02. It is confirmed exploited in the wild and must be patched as a priority.
Remediation deadline (US federal agencies): 2026-09-16
EPSS · FIRST.org
0.84%probability of exploitation in the next 30 days
Higher than 56% of scored CVEs
EPSS (Exploit Prediction Scoring System) estimates, from observed exploitation activity, how likely a CVE is to be exploited in the next 30 days. It complements CVSS, which measures severity, not likelihood. Score of 2026-10-16, recomputed daily by FIRST.org.
In-depth analysis on cveo.tech
We've published a detailed analysis of this CVE — exploitation, IOCs and mitigation.
CVSS v3.1 Score
Information
- Published
- 8 juil. 2026
- Updated
- 3 sept. 2026
- Status
- Analyzed
- Source
- security-advisories@github.com
Affected products
Weaknesses (CWE)
References (6)
- https://github.com/BerriAI/litellm/pull/26463Issue TrackingPatch
- https://github.com/BerriAI/litellm/releases/tag/v1.84.0ProductRelease Notes
- https://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95qMitigationPatchVendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-59822US Government Resource
- https://www.wiz.io/blog/ai-infrastructure-honeypotThird Party Advisory
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