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[ CVE-2026-107295 · Published 8 Oct 2026 ]

Pydantic AI Web chat UI (`Agent.to_web()`, `clai web`): a website visited by the developer can trigger agent runs and server-side tool execution on the local chat endpoint

CVSS 7.6 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 1.107.4 and 2.28.0, the Agent.to_web() and clai web development chat endpoint has missing request content-type validation. A website visited by a developer can submit a browser-compatible request to a loopback-hosted chat server, causing the served agent to run and execute tools with the privileges and credentials of the local process; client-relayed approval decisions also leave requires_approval=True tools exposed. Binding to localhost does not prevent a browser page from reaching the loopback address. This issue is fixed in versions 1.107.4 and 2.28.0.

[ Fixes ]Fixes and patches

  • pydantic-ai 1.107.4Fixed version · GitHub Advisories · pip package pydantic-ai: upgrade to 1.107.4 or later (affected >= 1.34.0, < 1.107.4)
  • pydantic-ai 2.28.0Fixed version · GitHub Advisories · pip package pydantic-ai: upgrade to 2.28.0 or later (affected >= 2.0.0b1, < 2.28.0)
  • pydantic-ai-slim 1.107.4Fixed version · GitHub Advisories · pip package pydantic-ai-slim: upgrade to 1.107.4 or later (affected >= 1.34.0, < 1.107.4)
  • pydantic-ai-slim 2.28.0Fixed version · GitHub Advisories · pip package pydantic-ai-slim: upgrade to 2.28.0 or later (affected >= 2.0.0b1, < 2.28.0)
  • 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