CVE-2026-59822: LiteLLM Authentication Bypass Vulnerability

HIGH
Advisory Identifier: GHSA-7488-6r32-c95q
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CWE-287
Published
Advisory Summary

CVE-2026-59822 is a HIGH authentication bypass vulnerability (CWE-287: Improper Authentication) affecting LiteLLM libraries in the PyPI ecosystem. The issue involves mcp authentication bypass via oauth2 passthrough fallback. Remediation is available by upgrading affected packages to version 1.84.0.

CVE-2026-59822 at a Glance

CVE Identifier CVE-2026-59822
GHSA Identifier GHSA-7488-6r32-c95q
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-287: Improper Authentication
Affected Product LiteLLM
Package Ecosystem PyPI
Published Date
Last Updated

How to Fix CVE-2026-59822

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: 1.84.0 
pip install litellm>=1.84.0
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-2026-59822, 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 1.84.0), 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-287: Improper Authentication, where when an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. 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

### Impact LiteLLM's MCP Streamable HTTP endpoint could allow an unauthenticated attacker to establish an authenticated MCP session using an arbitrary Bearer token. The MCP auth handler supported OAuth2 passthrough for upstream MCP servers, but the fallback path could replace failed LiteLLM key validation with an empty `UserAPIKeyAuth()` object. This allowed requests with a fabricated `Authorization` header to reach MCP tooling without a valid LiteLLM key. An attacker could use this to list and call configured MCP tools and access connected services exposed through MCP. ### Patches The issue is fixed in `1.84.0`. We recommend upgrading to `1.84.0` or later. ### Workarounds If upgrading is not immediately possible, disable MCP routes or block access to `/mcp/` and related MCP endpoints at your reverse proxy or API gateway. ### References * [v1.84.0](https://github.com/BerriAI/litellm/releases/tag/v1.84.0)

CVE-2026-59822 Affected LiteLLM Versions

1 component(s)
Fixed Versions:
1.84.0
Product / Package Ecosystem Affected Versions Fixed Version
litellm
pypi/litellm
PyPI
< 1.84.0
1.84.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95q
NVD — CVE-2026-59822 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-59822
LiteLLM Source Repository REPOSITORY
https://github.com/BerriAI/litellm/pull/26463
Security Fix Commit FIX COMMIT
https://github.com/BerriAI/litellm/commit/73869f0faf7d11ee21adcb5f91b8c33a340b6c2c
LiteLLM Source Repository REPOSITORY
https://github.com/BerriAI/litellm
LiteLLM Release RELEASE
https://github.com/BerriAI/litellm/releases/tag/v1.84.0

Frequently Asked Questions

What is CVE-2026-59822?
CVE-2026-59822 is a security vulnerability in LiteLLM involving MCP Authentication Bypass via OAuth2 Passthrough Fallback under CWE-287: Improper Authentication.
Which LiteLLM versions are affected?
Affected versions include releases prior to 1.84.0 across affected packages: litellm.
What version fixes CVE-2026-59822?
Upgrading to 1.84.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is litellm affected?
Yes, litellm is affected in releases prior to 1.84.0. Upgrade your dependency to 1.84.0 or later.
What CWE is associated with CVE-2026-59822?
CVE-2026-59822 is classified under 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.).
How can I check PyPI dependencies for CVE-2026-59822?
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-7488-6r32-c95q",
  "modified" : "2026-07-22T22:38:33Z",
  "published" : "2026-07-22T22:38:33Z",
  "aliases" : [ "CVE-2026-59822" ],
  "summary" : "LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback",
  "details" : "### Impact\n\nLiteLLM's MCP Streamable HTTP endpoint could allow an unauthenticated attacker to establish an authenticated MCP session using an arbitrary Bearer token.\n\nThe MCP auth handler supported OAuth2 passthrough for upstream MCP servers, but the fallback path could replace failed LiteLLM key validation with an empty `UserAPIKeyAuth()` object. This allowed requests with a fabricated `Authorization` header to reach MCP tooling without a valid LiteLLM key.\n\nAn attacker could use this to list and call configured MCP tools and access connected services exposed through MCP.\n\n### Patches\n\nThe issue is fixed in `1.84.0`.\n\nWe recommend upgrading to `1.84.0` or later.\n\n### Workarounds\n\nIf upgrading is not immediately possible, disable MCP routes or block access to `/mcp/` and related MCP endpoints at your reverse proxy or API gateway.\n\n### References\n\n* [v1.84.0](https://github.com/BerriAI/litellm/releases/tag/v1.84.0)",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "litellm"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.84.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95q"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-59822"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/BerriAI/litellm/pull/26463"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/BerriAI/litellm/commit/73869f0faf7d11ee21adcb5f91b8c33a340b6c2c"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/BerriAI/litellm"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/BerriAI/litellm/releases/tag/v1.84.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-287" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-22T22:38:33Z",
    "nvd_published_at" : "2026-07-08T20:16:57Z"
  }
}