Cyber Threat Intelligence
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HIGH · CVSS 8.2 CISA Known Exploited Vulnerability

CVE-2026-59822

BerriAI LiteLLM Improper Authentication Vulnerability

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.

CVSS
8.2
HIGH
EPSS
0.9%
30-day exploitation
Ransomware groups
0
recorded exploiting
Published
8 Jul 2026
CWE-287, CWE-306

Exploitation status

CISA Known Exploited Vulnerabilities

Listed by CISA on 2 September 2026. US federal agencies were required to remediate it by 16 September 2026.

EPSS — exploitation probability

FIRST puts the probability of exploitation activity in the next 30 days at 0.9%, which is higher than 56.5% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

Frequently asked questions

Is CVE-2026-59822 being exploited by ransomware groups?

No ransomware group in this database is currently recorded as exploiting CVE-2026-59822.

What does CVE-2026-59822 affect?

CVE-2026-59822 affects 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.

How severe is CVE-2026-59822?

CVE-2026-59822 is rated HIGH with a CVSS base score of 8.2. EPSS puts the probability of exploitation in the next 30 days at 0.9%, higher than 56.5% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 16 September 2026.

How should organisations respond to CVE-2026-59822?

Apply the vendor patch for BerriAI LiteLLM as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.