CVE-2026-12773: LiteLLM — HIGH

A weakness has been identified in BerriAI litellm up to 1.59.8. Affected is the function UserAPIKeyAuth of the file litellm/proxy/_experimental/mcp_server/auth/user_api_key_auth_mcp.py of the component MCP Proxy. Executing a manipulation can lead to improper authentication. The attack may be...

Full CISO analysis pending enrichment.

What systems are affected?

Package	Ecosystem	Vulnerable Range	Patched
LiteLLM	pip	—	No patch
51.0K OpenSSF 6.1 6 dependents Pushed today 48% patched ~41d to patch Full package profile →

Do you use LiteLLM? You're affected.

How severe is it?

CVSS 3.1

7.3 / 10

EPSS

N/A

Exploitation Status

No known exploitation

Sophistication

N/A

What is the attack surface?

AV Network

AC Low

PR None

UI None

S Unchanged

C Low

I Low

A Low

What should I do?

No patch available

Monitor for updates. Consider compensating controls or temporary mitigations.

Which compliance frameworks are affected?

Compliance analysis pending. Sign in for full compliance mapping when available.

Frequently Asked Questions

What is CVE-2026-12773?

A weakness has been identified in BerriAI litellm up to 1.59.8. Affected is the function UserAPIKeyAuth of the file litellm/proxy/_experimental/mcp_server/auth/user_api_key_auth_mcp.py of the component MCP Proxy. Executing a manipulation can lead to improper authentication. The attack may be launched remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure.

Is CVE-2026-12773 actively exploited?

No confirmed active exploitation of CVE-2026-12773 has been reported, but organizations should still patch proactively.

How to fix CVE-2026-12773?

No patch is currently available. Monitor vendor advisories for updates.

What is the CVSS score for CVE-2026-12773?

CVE-2026-12773 has a CVSS v3.1 base score of 7.3 (HIGH).

What are the technical details?

Original Advisory

A weakness has been identified in BerriAI litellm up to 1.59.8. Affected is the function UserAPIKeyAuth of the file litellm/proxy/_experimental/mcp_server/auth/user_api_key_auth_mcp.py of the component MCP Proxy. Executing a manipulation can lead to improper authentication. The attack may be launched remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure.

Weaknesses (CWE)

CWE-287 Improper Authentication

CWE-287 — Improper Authentication: When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.