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Vulnerabilities

Vulnerability · CVE-2026-59822

BerriAI LiteLLM Improper Authentication Vulnerability

Published Jul 8, 2026 · catalog updated Sep 3, 2026 · BerriAI LiteLLM

Severity
High8.8
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
0.8%
Remediation
Remediation guidance
Affected products
cpe litellm/litellm · vendor BerriAI LiteLLM

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.

Technical analysis

Mechanism and impact are interpreted from ingested advisories — not independent exploit research.

  • CWE classification

    Improper Authentication · Missing Authentication for Critical Function

  • Prerequisites and impact

    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.

How to fix CVE-2026-59822

  • Recommended remediation

    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. CISA due date Sep 16, 2026.

  • Official advisories

What to do

Three reads of the same public record: the decision, the versions on file, and the signals. Confirm the vendor advisory before you patch. This page does not publish exploit steps.

Executive

Treat this as an active risk. CVE-2026-59822 is a high issue in BerriAI LiteLLM (CVSS 8.8). CISA lists it as known exploited since Jul 8, 2026. Next step: 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.

System administrator

Check whether BerriAI LiteLLM is installed. Ranges on record: litellm/litellm; BerriAI LiteLLM. 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.

Security analyst

CVSS 8.8. EPSS 0.8%. CISA lists it as known exploited since Jul 8, 2026. Weaknesses: CWE-287, CWE-306. Sources: cisa_kev, cve_org, epss, nvd. Exploit links, when listed below, point at the original publisher.

Related intelligence

  • Exploitation evidence

    Confirmed in CISA KEV since Jul 8, 2026. Listed in CISA KEV and VulnCheck KEV.

  • Safe detection guidance

    Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Jul 8, 2026 · Catalog

    Detected

    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 va

  2. Sep 2, 2026 · CISA KEV

    Known exploited

    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

  3. Sep 3, 2026 · Catalog

    Updated

    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 va

  4. Sep 16, 2026 · CISA KEV

    Remediation due

    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

Affected versions

Enter an installed version to get a verified affected / not-affected result against the ranges below.

  • cpe litellm/litellmversion unspecified
  • vendor BerriAI LiteLLMversion unspecified

Sources

  • CISA KEVConfirmed exploitationCVE-2026-59822

    BerriAI LiteLLM contains an improper authentication vulnerability in the MCP Streamable HTTP endpoint that could allow an unauthenticated attacker to establish an authenticated MCP session using an arbitrary Bearer token.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2026-59822

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-59822

    30-day exploitation probability 0.8%

    first.org
  • NIST NVDVulnerability recordCVE-2026-59822

    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

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2026-59822

    BerriAI LiteLLM contains an improper authentication vulnerability in the MCP Streamable HTTP endpoint that could allow an unauthenticated attacker to establish an authenticated MCP session using an arbitrary Bearer token.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.