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Public proof of conceptFix available

CVE-2026-12773

A public proof of concept exists; no exploitation attested.

  • Published2026-06-21
  • Fixed in1.59.9
  • WeaknessCWE-287 · CWE-303

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2026-06-2104:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-12773?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-12773?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Litellm
BranchAffectedFixed in
1.59< 1.59.91.59.9
litellm
BranchAffectedFixed in
1.84< 1.84.01.84.0

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Litellm to 1.59.9

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CISA-ADPSSVC decisionpoc2026-06-22
  • OpenCVESSVC decisionpoc—
  • CNACVSS 4.05.5read 2026-10-23
  • CNACVSS 3.17.3read 2026-10-23
  • NVDCVSS 3.19.8read 2026-10-23
  • CNACVSS 2.07.5read 2026-10-23
  • CNAweakness (CWE)CWE-287, CWE-303read 2026-10-23
  • FIRST EPSSEPSS score1.0 %2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 4.0 vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published
2026-06-21
Last Modified
2026-07-15
NVD status
Modified

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?

A proof-of-concept exploit exists for CVE-2026-12773, but active exploitation has not been confirmed at this time.

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

CVE-2026-12773 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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