CVE-2026-59822: LiteLLM proxy MCP endpoint authentication bypass with fabricated Bearer token

Exploited in the wild High 8.8 EPSS 0.8%

In the LiteLLM proxy (AI gateway) before 1.84.0, the MCP Streamable HTTP endpoint's OAuth2-passthrough fallback replaced a failed LiteLLM key check with an empty auth object, so an unauthenticated attacker sending any made-up Authorization header could list and call the configured MCP tools and reach the services behind them. It is fixed in LiteLLM 1.84.0, and CISA added it to the Known Exploited Vulnerabilities catalog on 2026-09-02.

CVE-2026-59822CVE identifier
8.8CVSS 4.0 base score (high)
2026-09-02added to CISA's exploited list (US federal deadline 2026-09-16)
0.8%EPSS: chance of exploitation in the next 30 days (higher than 58% of CVEs)
2026-07-08published

What do these terms mean? CVE · CVSS score · exploited (KEV) · EPSS · backported fix · all terms

What to do now

Check whether you run the affected software and which version (commands below).
Install the fixed version for your system: see “Patch it” below.
Restart the LiteLLM proxy after upgrading.
If you cannot patch today, apply the temporary mitigation below and patch as soon as possible.
Because this flaw is being exploited, also check the server for signs of compromise.

Affected and fixed versions

Affected:

LiteLLM before 1.84.0

Fixed in:

LiteLLM 1.84.0

Am I affected?

pip show litellm | grep -i ^version

Patch it

Use the commands for your system. Distribution packages often keep an older version number with the fix backported, so compare with the fixed package versions in the table below, not only with the upstream version.

Docker images

docker pull ghcr.io/berriai/litellm:<release-tag 1.84.0 or later>
# recreate the proxy container from the new image

Built from source

pip install --upgrade 'litellm[proxy]>=1.84.0'
# then restart the litellm proxy process

General update steps for every system are on the Linux and Unix & BSD pages; after updating, see which services to restart.

If you cannot patch yet

If you cannot upgrade immediately, disable MCP routes or block access to /mcp/ and related MCP endpoints at your reverse proxy or API gateway (vendor workaround).

CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

https://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95q ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-59822

Sources

Page generated automatically from official sources on 2026-11-03 18:05 UTC and reviewed by an editor. Always confirm with your vendor's advisory.