CVE-2026-59822: BerriAI LiteLLM Improper Authentication Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 2 Sep 2026, 56 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 0.8%
EPSS score, percentile 57.6 of all scored records
- How severe?
- 8.8 High
CVSS v4.0 base score, given by the CNA
- What should I do?
CISA deadline 16 Sep 2026. Apply mitigations in accordance with vendor instructions … Full text
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- < 1.84.0
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
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 for this action: 16 September 2026.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
- https://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95q
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- 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
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | < 1.84.0 |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this vulnerability
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.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2026-59822 to its Known Exploited Vulnerabilities (KEV) catalog on 2 Sep 2026.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 16 Sep 2026.
- The CVE record was published on 8 Jul 2026, 56 days before it was added to KEV.
- The CVE record carries a CVSS v4.0 base score of 8.8 (High), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.8% (percentile 57.6), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact partial.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 8 Jul 2026 | CVE record published |
| 2 Sep 2026 | Added to CISA KEV |
| 3 Sep 2026 | CVE record last updated |
| 16 Sep 2026 | CISA due date for the required action |
References
- https://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95q
- https://github.com/BerriAI/litellm/pull/26463
- https://github.com/BerriAI/litellm/commit/73869f0faf7d11ee21adcb5f91b8c33a340b6c2c
- https://github.com/BerriAI/litellm/releases/tag/v1.84.0
More exploited BerriAI vulnerabilities
- CVE-2026-42271: BerriAI LiteLLM Command Injection Vulnerability
- CVE-2026-42208: BerriAI LiteLLM SQL Injection Vulnerability