CVE-2026-12771: LiteLLM M2M JWT Handler Has Improper Vulnerability

LOW
Advisory Identifier: GHSA-qmf3-4767-5fg3
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CVSS 5.0
CWE-266 CWE-285
Published
Advisory Summary

CVE-2026-12771 is a LOW (CVSS 5.0) m2m jwt handler has improper vulnerability (CWE-266: Incorrect Privilege Assignment) affecting LiteLLM libraries in the PyPI ecosystem. The issue involves m2m jwt handler has improper authorization. Remediation is available in the latest vendor maintenance releases.

CVE-2026-12771 at a Glance

CVE Identifier CVE-2026-12771
GHSA Identifier GHSA-qmf3-4767-5fg3
Severity LOW
CVSS v3.1 Base Score 5.0
CWE Classification CWE-266: Incorrect Privilege Assignment
Affected Product LiteLLM
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.0

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability Low (A:L)

How to Fix CVE-2026-12771

To remediate this vulnerability, upgrade all affected LiteLLM dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

litellm fixed: Latest secure release 
pip install litellm>=Latest secure release
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show litellm

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-12771, inspect your installed packages using pip:

pip show litellm

Analyze the terminal output to locate any version of LiteLLM in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The pip show litellm command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-266: Incorrect Privilege Assignment, where a product incorrectly assigns a privilege to a particular actor, creating an unintended sphere of control for that actor. In LiteLLM, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

A vulnerability was identified in BerriAI litellm up to 1.82.2. This affects an unknown function of the file litellm/proxy/auth/user_api_key_auth.py of the component M2M JWT Handler. Such manipulation leads to improper authorization. The attack can be launched remotely. A high complexity level is associated with this attack. The exploitability is reported as difficult. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure.

CVE-2026-12771 Affected LiteLLM Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
litellm
pypi/litellm
PyPI
≤ 1.82.2

References

vuldb.com/cve/cve-2026-12771 WEB
https://vuldb.com/cve/CVE-2026-12771
vuldb.com/submit/811280 WEB
https://vuldb.com/submit/811280
vuldb.com/vuln/372513 WEB
https://vuldb.com/vuln/372513
vuldb.com/vuln/372513/cti WEB
https://vuldb.com/vuln/372513/cti
NVD — CVE-2026-12771 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-12771
LiteLLM Source Repository REPOSITORY
https://gist.github.com/YLChen-007/70e4e106527f74ddf17953ff0f6c248d
LiteLLM Source Repository REPOSITORY
https://github.com/BerriAI/litellm

Frequently Asked Questions

What is CVE-2026-12771?
CVE-2026-12771 is a security vulnerability in LiteLLM involving M2M JWT Handler Has Improper Authorization under CWE-266: Incorrect Privilege Assignment.
Which LiteLLM versions are affected?
Affected versions include releases prior to current release patches across affected packages: litellm.
What version fixes CVE-2026-12771?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is litellm affected?
Yes, litellm is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2026-12771?
CVE-2026-12771 has a CVSS v3.1 base score of 5.0 (LOW) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L.
What CWE is associated with CVE-2026-12771?
CVE-2026-12771 is classified under CWE-266: Incorrect Privilege Assignment (A product incorrectly assigns a privilege to a particular actor, creating an unintended sphere of control for that actor.).
How can I check PyPI dependencies for CVE-2026-12771?
Run the dependency tree command: 'pip show litellm'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-qmf3-4767-5fg3",
  "modified" : "2026-09-10T19:43:35Z",
  "published" : "2026-06-21T03:30:24Z",
  "aliases" : [ "CVE-2026-12771" ],
  "summary" : "LiteLLM: M2M JWT Handler Has Improper Authorization",
  "details" : "A vulnerability was identified in BerriAI litellm up to 1.82.2. This affects an unknown function of the file litellm/proxy/auth/user_api_key_auth.py of the component M2M JWT Handler. Such manipulation leads to improper authorization. The attack can be launched remotely. A high complexity level is associated with this attack. The exploitability is reported as difficult. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "litellm"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.82.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-12771"
  }, {
    "type" : "WEB",
    "url" : "https://gist.github.com/YLChen-007/70e4e106527f74ddf17953ff0f6c248d"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/BerriAI/litellm"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/cve/CVE-2026-12771"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/submit/811280"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/vuln/372513"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/vuln/372513/cti"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-266", "CWE-285" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-10T19:43:35Z",
    "nvd_published_at" : "2026-06-21T02:16:41Z"
  }
}