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[ CVE-2026-107292 · Published 8 Oct 2026 ]

Pydantic AI Web chat UI (`Agent.to_web()`, `clai web`): the local chat endpoint does not validate the `Host` header

CVSS 6.4 EPSS <1%Fix available

[ Description ]Official description

Pydantic AI is a Python agent framework for building applications and workflows with Generative AI. From 1.34.0 until 2.30.0, the Agent.to_web() and clai web development chat server does not validate the Host header, allowing a website visited by a developer to use DNS rebinding to reach a loopback-hosted agent as a same-origin service. The hostile page can read the served UI and submit chat requests that execute agent tools with the local process's privileges and credentials, causing data disclosure or unwanted side effects. Binding to localhost, Origin checks, and CSRF tokens do not prevent the same-origin DNS rebinding path. This issue is fixed in versions 1.107.5 and 2.30.0.

[ Fixes ]Fixes and patches

  • pydantic-ai 1.107.5Fixed version · GitHub Advisories · pip package pydantic-ai: upgrade to 1.107.5 or later (affected >= 1.34.0, < 1.107.5)
  • pydantic-ai 2.30.0Fixed version · GitHub Advisories · pip package pydantic-ai: upgrade to 2.30.0 or later (affected >= 2.0.0b1, < 2.30.0)
  • pydantic-ai-slim 1.107.5Fixed version · GitHub Advisories · pip package pydantic-ai-slim: upgrade to 1.107.5 or later (affected >= 1.34.0, < 1.107.5)
  • pydantic-ai-slim 2.30.0Fixed version · GitHub Advisories · pip package pydantic-ai-slim: upgrade to 2.30.0 or later (affected >= 2.0.0b1, < 2.30.0)
  • Patch on github.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD
  • Patch on github.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD
  • Patch on github.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD
  • Patch on github.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD

[ Packages ]Affected open-source packages

[ References ]References