CVE-2026-59822: CWE-287: Improper Authentication in BerriAI litellm
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.
AI Analysis
Technical Summary
CVE-2026-59822 describes an improper authentication vulnerability (CWE-287) in BerriAI's LiteLLM proxy server before version 1.84.0. The vulnerability arises because the MCP Streamable HTTP endpoint accepts a fabricated Authorization header, triggering an OAuth2 passthrough fallback that replaces failed key validation with an empty UserAPIKeyAuth() object. This allows unauthenticated requests to reach MCP tooling without a valid LiteLLM key, effectively bypassing authentication controls. The vulnerability has a CVSS 4.0 score of 8.8 (high severity).
Potential Impact
Exploitation allows unauthenticated attackers to bypass LiteLLM's key validation and access MCP tooling endpoints without valid credentials. This could lead to unauthorized use of API functionality intended to be protected by authentication, potentially exposing sensitive operations or data accessible via the MCP tooling.
Mitigation Recommendations
Upgrade LiteLLM to version 1.84.0 or later, where this authentication bypass vulnerability is fixed. Patch status is not explicitly stated as 'official-fix' in the advisory, but the description confirms the issue is resolved in 1.84.0. No other mitigations are indicated.
CVE-2026-59822: CWE-287: Improper Authentication in BerriAI litellm
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 v4.0
Score 8.8high
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-59822 describes an improper authentication vulnerability (CWE-287) in BerriAI's LiteLLM proxy server before version 1.84.0. The vulnerability arises because the MCP Streamable HTTP endpoint accepts a fabricated Authorization header, triggering an OAuth2 passthrough fallback that replaces failed key validation with an empty UserAPIKeyAuth() object. This allows unauthenticated requests to reach MCP tooling without a valid LiteLLM key, effectively bypassing authentication controls. The vulnerability has a CVSS 4.0 score of 8.8 (high severity).
Potential Impact
Exploitation allows unauthenticated attackers to bypass LiteLLM's key validation and access MCP tooling endpoints without valid credentials. This could lead to unauthorized use of API functionality intended to be protected by authentication, potentially exposing sensitive operations or data accessible via the MCP tooling.
Mitigation Recommendations
Upgrade LiteLLM to version 1.84.0 or later, where this authentication bypass vulnerability is fixed. Patch status is not explicitly stated as 'official-fix' in the advisory, but the description confirms the issue is resolved in 1.84.0. No other mitigations are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-07-07T15:00:50.978Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4ea889c9d9e3dbe3a526a5
Added to database: 07/08/2026, 19:44:09 UTC
Last enriched: 07/16/2026, 10:06:40 UTC
Last updated: 08/22/2026, 22:52:15 UTC
Views: 209
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