CVE-2026-59822: listed in the CISA KEV catalog

CVE-2026-59822 · EPSS 1% · KEV 2026-09-02 · patch available

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.

Is CVE-2026-59822 exploited?

• Listed in the CISA KEV catalog on 2026-09-02.
• Federal remediation due 2026-09-16.
• Past that date by 27 days.
• EPSS puts exploitation in the next 30 days at 1%.
• Public exploit code: none found in monitored sources.

Which products and versions are affected?

• Open Source · LiteLLM · <1.84.0
• Open Source · LiteLLM · <1.83.10-stable
• Open Source · LiteLLM · <1.82.0-stable
• Open Source · LiteLLM · <1.83.7-stable

Is there a patch?

• LiteLLM 1.84.0
• LiteLLM 1.83.10-stable
• LiteLLM 1.82.0-stable
• LiteLLM 1.83.7-stable

What PlainSec published about CVE-2026-59822

• Wiz Flags AI Gateways as a New Attack Plane (2026-08-28)

Primary sources

• NVD record
• CISA KEV catalog

What this record does not say

• No CVSS score from NVD.

KEV and EPSS are re-checked daily. Record last updated 2026-09-24.