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Medium

LiteLLM: MCP Proxy Has Improper Authentication

  • Disclosed: 21.06.2026
  • Updated: 11.10.2026 15:18

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.

Affected software

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PlatformPackageVulnerable versionsFixed in
Python (PyPI) litellm < 1.84.0 1.84.0

References

CVSS score 7.3/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Weakness (CWE)
CWE-287, CWE-303
Platform
Python (PyPI)
Package
litellm
Disclosed
21.06.2026
Updated
11.10.2026 15:18

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2026-4067 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-4jcj-7x88-m979 - CC BY 4.0

Vulnerability history: litellm

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (42) in the archive
Total entries
42
First → latest
04.2024 09.2026
Without a fix
14
Exploited in attacks
3

Severity breakdown

  • Critical 7
  • High 17
  • Medium 8
  • Low 9
  • Unrated 1

Disclosures per year

Severity:
  1. LiteLLM vulnerable to server-side template injection in the /prompts/test endpoint
    Critical · 9.8 CVE-2026-37004 < 1.83.7 1.83.7
  2. LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback
    High Exploited in attacks CVE-2026-59822 < 1.84.0 1.84.0
  3. LiteLLM: MCP Proxy Has Improper Authentication this entry
    Medium · 7.3 CVE-2026-12773 < 1.84.0 1.84.0
  4. LiteLLM: Authentication Bypass via Host Header Injection
    Critical · 9.8 CVE-2026-49468 < 1.84.0 1.84.0
  5. LiteLLM allows a user to modify their own user_role via the /user/update endpoint
    High · 8.8 CVE-2026-47102 < 1.83.10 1.83.10
  6. LiteLLM allows an authenticated internal_user to create API keys with access to routes that their role does not permit
    High · 8.8 CVE-2026-47101 < 1.83.14 1.83.14
  7. LiteLLM has a sandbox escape in custom-code guardrail
    High · 8.8 CVE-2026-40217 >= 1.81.8, < 1.83.10 1.83.10
  8. LiteLLM: Authenticated command execution via MCP stdio test endpoints
    High · 8.8 Exploited in attacks CVE-2026-42271 >= 1.74.2, < 1.83.7 1.83.7
  9. LiteLLM has SQL Injection in Proxy API key verification
    Critical · 9.8 Exploited in attacks CVE-2026-42208 >= 1.81.16, < 1.83.7 1.83.7
  10. LiteLLM: Server-Side Template Injection in /prompts/test endpoint
    High CVE-2026-42203 >= 1.80.5, < 1.83.7 1.83.7
  11. LiteLLM: Password hash exposure and pass-the-hash authentication bypass
    High ghsa-69x8-hrgq-fjj8 < 1.83.0 1.83.0
  12. LiteLLM: Authentication bypass via OIDC userinfo cache key collision
    Critical CVE-2026-35030 < 1.83.0 1.83.0
  13. LiteLLM: Privilege escalation via unrestricted proxy configuration endpoint
    High CVE-2026-35029 < 1.83.0 1.83.0
  14. Two LiteLLM versions published containing credential harvesting malware
    Critical ghsa-5mg7-485q-xm76 >= 1.82.7, <= 1.82.8 no fix
  15. LiteLLM Has an Improper Authorization Vulnerability
    High · 8.1 CVE-2025-0628 < 1.61.15 1.61.15
  16. LiteLLM Has a Leakage of Langfuse API Keys
    High · 7.5 CVE-2025-0330 <= 1.52.1 no fix
  17. LiteLLM Reveals Portion of API Key via a Logging File
    High · 7.5 CVE-2024-9606 < 1.44.12 1.44.12
  18. LiteLLM Vulnerable to Denial of Service (DoS) via Crafted HTTP Request
    High · 7.5 CVE-2024-8984 < 1.56.2 1.56.2
  19. LiteLLM Vulnerable to Remote Code Execution (RCE)
    High · 8.8 CVE-2024-6825 >= 1.40.3.dev2, <= 1.40.12 no fix
  20. LiteLLM Vulnerable to Denial of Service (DoS)
    High · 7.5 CVE-2024-10188 < 1.53.1.dev1 1.53.1.dev1
Show more (5) Showing 20 of 25

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