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Known exploited vulnerability

CVE-2026-59822

highCVSS 4.0 8.8In CISA KEVEPSS 0.84%Published · BerriAI

The short answer

CVE-2026-59822 affects BerriAI litellm and is rated high (CVSS 8.8). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-09-02: attackers are using it, so patch it first. Fixed versions are published for litellm (1.84.0).

What it is

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.84.0, LiteLLM's MCP Streamable HTTP endpoint allowed an unauthenticated attacker to use a fabricated Authorization header to trigger an OAuth2 passthrough fallback path that replaced failed LiteLLM key validation with an empty UserAPIKeyAuth() object, allowing requests to reach MCP tooling without a valid LiteLLM key. This issue is fixed in version 1.84.0.

Weakness: CWE-287, CWE-306.

Severity

8.8 high

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/E:X/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

Exploited (CISA KEV)

Yes, since Sep 2, 2026

Federal due date Sep 16, 2026

EPSS, next 30 days

0.84%

Higher than 58% of scored CVEs

How it can be exploited

Attack vector
Network
Attack complexity
Low
Attack requirements
None
Privileges required
None
User interaction
None
Confidentiality impact
High
Integrity impact
Low
Availability impact
None

What CISA says to do

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…

Affected packages and fixed versions

PackageEcosystemFixed inAdvisory
litellmPyPI1.84.0GHSA-7488-6r32-c95q

Is it in your code? Drop your lockfile into the free vulnerability check, or let vulnerability watch check your repository every day and open the upgrade as a pull request.

Affected products

litellm. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2026-59822 being exploited?

Yes. CISA added CVE-2026-59822 to its Known Exploited Vulnerabilities catalog on 2026-09-02, with a federal remediation due date of 2026-09-16.

How do I fix CVE-2026-59822?

Upgrade to a fixed version: litellm (PyPI) 1.84.0. CISA's 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…

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.

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