All vulnerabilities
CVE-2026-107295GHSA-h4xc-3qfq-jf93PYSEC-2026-4278PYSEC-2026-4287

pydantic-ai: 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

pydantic pydantic-aipipLibraries & packages
Open in ThreatlineRecord JSON
CVSS
7.6High
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.16%Chance of exploitation activity in the next 30 days, higher than 4% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in1.107.4Also 2.28.0GitHub
Published8 Oct 2026Updated 15 Oct 2026CVE List

What fixes it

  • 1.107.4pydantic-ai, pipGitHub
  • 2.28.0pydantic-ai, pipGitHub
  • 1.107.4pydantic-ai-slim, pipGitHub
  • 2.28.0pydantic-ai-slim, pipGitHub
  • 1.107.4pydantic-ai, PyPIOSVpip install "pydantic-ai>=1.107.4"
  • 2.28.0pydantic-ai, PyPIOSVpip install "pydantic-ai>=2.28.0"
Show all 8 fixed versions
  • 1.107.4pydantic-ai-slim, PyPIOSVpip install "pydantic-ai-slim>=1.107.4"
  • 2.28.0pydantic-ai-slim, PyPIOSVpip install "pydantic-ai-slim>=2.28.0"

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

Summary

The Pydantic AI development web chat UI (Agent.to_web(), clai web) did not check the content type of requests to its chat endpoint. This allowed a website visited by a developer to submit a request to a chat UI running on that developer's machine, causing the served agent to run and to execute its tools with the privileges and credentials of the local process.

Binding the web UI to localhost — the default — does not prevent this, because a page open in the developer's browser can reach the loopback address.

Impact

Applications and developers serving an agent through Agent.to_web() or clai web. The consequences depend on the tools the served agent exposes, and can include data disclosure as well as unwanted tool side effects. Tools marked requires_approval=True were not protected either, because the endpoint trusts approval decisions relayed by the client.

Mitigation

Upgrade to a patched version. The chat endpoint now requires Content-Type: application/json and rejects other requests before the request body is parsed and before the agent runs. The bundled chat UI already sends this header; scripts and other non-browser clients that call the endpoint directly may need to be updated to send it.

If you cannot upgrade, don't run the web UI while browsing untrusted sites, stop it when you aren't using it, and don't serve an agent with side-effecting tools through it.

Credits

  • Thai Son Dinh from VinSOC Labs (R&D)

Text from GitHub Advisory Database

Affected versions 190

  • pydantic-ai, pip>= 1.34.0, < 1.107.4GitHub
  • pydantic-ai, pip>= 2.0.0b1, < 2.28.0GitHub
  • pydantic-ai-slim, pip>= 1.34.0, < 1.107.4GitHub
  • pydantic-ai-slim, pip>= 2.0.0b1, < 2.28.0GitHub
  • pydantic-aiaffected: >= 1.34.0, < 1.107.4CVE List
  • pydantic-aiaffected: >= 2.0.0b1, < 2.28.0CVE List
  • pydantic-ai-slimaffected: >= 1.34.0, < 1.107.4CVE List
  • pydantic-ai-slimaffected: >= 2.0.0b1, < 2.28.0CVE List
  • pydantic-ai, PyPIfrom 1.34.0, fixed in 1.107.4OSV
  • pydantic-ai, PyPI1.100.0OSV
  • pydantic-ai, PyPI1.101.0OSV
  • pydantic-ai, PyPI1.102.0OSV
  • pydantic-ai, PyPI1.103.0OSV
  • pydantic-ai, PyPI1.104.0OSV
  • pydantic-ai, PyPI1.105.0OSV
  • pydantic-ai, PyPI1.106.0OSV
  • pydantic-ai, PyPI1.107.0OSV
  • pydantic-ai, PyPI1.107.1OSV
  • pydantic-ai, PyPI1.107.2OSV
  • pydantic-ai, PyPI1.34.0OSV
  • pydantic-ai, PyPI1.35.0OSV
  • pydantic-ai, PyPI1.36.0OSV
  • pydantic-ai, PyPI1.37.0OSV
  • pydantic-ai, PyPI1.38.0OSV
  • pydantic-ai, PyPI1.39.0OSV
  • pydantic-ai, PyPI1.39.1OSV
  • pydantic-ai, PyPI1.40.0OSV
  • pydantic-ai, PyPI1.41.0OSV
  • pydantic-ai, PyPI1.42.0OSV
  • pydantic-ai, PyPI1.43.0OSV
  • pydantic-ai, PyPI1.44.0OSV
  • pydantic-ai, PyPI1.46.0OSV
  • pydantic-ai, PyPI1.47.0OSV
  • pydantic-ai, PyPI1.48.0OSV
  • pydantic-ai, PyPI1.49.0OSV
  • pydantic-ai, PyPI1.50.0OSV
  • pydantic-ai, PyPI1.51.0OSV
  • pydantic-ai, PyPI1.52.0OSV
  • pydantic-ai, PyPI1.53.0OSV
  • pydantic-ai, PyPI1.54.0OSV
  • pydantic-ai, PyPI1.55.0OSV
  • pydantic-ai, PyPI1.56.0OSV
  • pydantic-ai, PyPI1.57.0OSV
  • pydantic-ai, PyPI1.58.0OSV
  • pydantic-ai, PyPI1.59.0OSV
  • pydantic-ai, PyPI1.60.0OSV
  • pydantic-ai, PyPI1.61.0OSV
  • pydantic-ai, PyPI1.62.0OSV
  • pydantic-ai, PyPI1.63.0OSV
  • pydantic-ai, PyPI1.64.0OSV
  • pydantic-ai, PyPI1.65.0OSV
  • pydantic-ai, PyPI1.66.0OSV
  • pydantic-ai, PyPI1.67.0OSV
  • pydantic-ai, PyPI1.68.0OSV
  • pydantic-ai, PyPI1.69.0OSV
  • pydantic-ai, PyPI1.70.0OSV
  • pydantic-ai, PyPI1.71.0OSV
  • pydantic-ai, PyPI1.72.0OSV
  • pydantic-ai, PyPI1.73.0OSV
  • pydantic-ai, PyPIfrom 2.0.0b1, fixed in 2.28.0OSV
  • pydantic-ai, PyPI2.0.0OSV
  • pydantic-ai, PyPI2.0.0b1OSV
  • pydantic-ai, PyPI2.0.0b2OSV
  • pydantic-ai, PyPI2.0.0b3OSV
  • pydantic-ai, PyPI2.0.0b4OSV
  • pydantic-ai, PyPI2.0.0b5OSV
  • pydantic-ai, PyPI2.0.0b6OSV
  • pydantic-ai, PyPI2.0.0b7OSV
  • pydantic-ai, PyPI2.1.0OSV
  • pydantic-ai, PyPI2.10.0OSV
  • pydantic-ai, PyPI2.11.0OSV
  • pydantic-ai, PyPI2.12.0OSV
  • pydantic-ai, PyPI2.13.0OSV
  • pydantic-ai, PyPI2.14.0OSV
  • pydantic-ai, PyPI2.14.1OSV
  • pydantic-ai, PyPI2.15.0OSV
  • pydantic-ai, PyPI2.16.0OSV
  • pydantic-ai, PyPI2.17.0OSV
  • pydantic-ai, PyPI2.18.0OSV
  • pydantic-ai, PyPI2.19.0OSV
  • pydantic-ai, PyPI2.2.0OSV
  • pydantic-ai, PyPI2.20.0OSV
  • pydantic-ai, PyPI2.21.0OSV
  • pydantic-ai, PyPI2.22.0OSV
  • pydantic-ai, PyPI2.23.0OSV
  • pydantic-ai, PyPI2.24.0OSV
  • pydantic-ai, PyPI2.25.0OSV
  • pydantic-ai, PyPI2.26.0OSV
  • pydantic-ai, PyPI2.27.0OSV
  • pydantic-ai, PyPI2.27.1OSV
  • pydantic-ai, PyPI2.3.0OSV
  • pydantic-ai, PyPI2.4.0OSV
  • pydantic-ai, PyPI2.5.0OSV
  • pydantic-ai, PyPI2.5.1OSV
  • pydantic-ai, PyPI2.6.0OSV
  • pydantic-ai, PyPI2.7.0OSV
  • pydantic-ai, PyPI2.8.0OSV
  • pydantic-ai, PyPI2.9.0OSV
  • pydantic-ai, PyPI2.9.1OSV
  • pydantic-ai-slim, PyPIfrom 1.34.0, fixed in 1.107.4OSV
  • pydantic-ai-slim, PyPI1.100.0OSV
  • pydantic-ai-slim, PyPI1.101.0OSV
  • pydantic-ai-slim, PyPI1.102.0OSV
  • pydantic-ai-slim, PyPI1.103.0OSV
  • pydantic-ai-slim, PyPI1.104.0OSV
  • pydantic-ai-slim, PyPI1.105.0OSV
  • pydantic-ai-slim, PyPI1.106.0OSV
  • pydantic-ai-slim, PyPI1.107.0OSV
  • pydantic-ai-slim, PyPI1.107.1OSV
  • pydantic-ai-slim, PyPI1.107.2OSV
  • pydantic-ai-slim, PyPI1.34.0OSV
  • pydantic-ai-slim, PyPI1.35.0OSV
  • pydantic-ai-slim, PyPI1.36.0OSV
  • pydantic-ai-slim, PyPI1.37.0OSV
  • pydantic-ai-slim, PyPI1.38.0OSV
  • pydantic-ai-slim, PyPI1.39.0OSV
  • pydantic-ai-slim, PyPI1.39.1OSV
  • pydantic-ai-slim, PyPI1.40.0OSV
  • pydantic-ai-slim, PyPI1.41.0OSV
  • pydantic-ai-slim, PyPI1.42.0OSV
  • pydantic-ai-slim, PyPI1.43.0OSV
  • pydantic-ai-slim, PyPI1.44.0OSV
  • pydantic-ai-slim, PyPI1.46.0OSV
  • pydantic-ai-slim, PyPI1.47.0OSV
  • pydantic-ai-slim, PyPI1.48.0OSV
  • pydantic-ai-slim, PyPI1.49.0OSV
  • pydantic-ai-slim, PyPI1.50.0OSV
  • pydantic-ai-slim, PyPI1.51.0OSV
  • pydantic-ai-slim, PyPI1.52.0OSV
  • pydantic-ai-slim, PyPI1.53.0OSV
  • pydantic-ai-slim, PyPI1.54.0OSV
  • pydantic-ai-slim, PyPI1.55.0OSV
  • pydantic-ai-slim, PyPI1.56.0OSV
  • pydantic-ai-slim, PyPI1.57.0OSV
  • pydantic-ai-slim, PyPI1.58.0OSV
  • pydantic-ai-slim, PyPI1.59.0OSV
  • pydantic-ai-slim, PyPI1.60.0OSV
  • pydantic-ai-slim, PyPI1.61.0OSV
  • pydantic-ai-slim, PyPI1.62.0OSV
  • pydantic-ai-slim, PyPI1.63.0OSV
  • pydantic-ai-slim, PyPI1.64.0OSV
  • pydantic-ai-slim, PyPI1.65.0OSV
  • pydantic-ai-slim, PyPI1.66.0OSV
  • pydantic-ai-slim, PyPI1.67.0OSV
  • pydantic-ai-slim, PyPI1.68.0OSV
  • pydantic-ai-slim, PyPI1.69.0OSV
  • pydantic-ai-slim, PyPI1.70.0OSV
  • pydantic-ai-slim, PyPI1.71.0OSV
  • pydantic-ai-slim, PyPI1.72.0OSV
  • pydantic-ai-slim, PyPI1.73.0OSV
  • pydantic-ai-slim, PyPIfrom 2.0.0b1, fixed in 2.28.0OSV
  • pydantic-ai-slim, PyPI2.0.0OSV
  • pydantic-ai-slim, PyPI2.0.0b1OSV
  • pydantic-ai-slim, PyPI2.0.0b2OSV
  • pydantic-ai-slim, PyPI2.0.0b3OSV
  • pydantic-ai-slim, PyPI2.0.0b4OSV
  • pydantic-ai-slim, PyPI2.0.0b5OSV
  • pydantic-ai-slim, PyPI2.0.0b6OSV
  • pydantic-ai-slim, PyPI2.0.0b7OSV
  • pydantic-ai-slim, PyPI2.1.0OSV
  • pydantic-ai-slim, PyPI2.10.0OSV
  • pydantic-ai-slim, PyPI2.11.0OSV
  • pydantic-ai-slim, PyPI2.12.0OSV
  • pydantic-ai-slim, PyPI2.13.0OSV
  • pydantic-ai-slim, PyPI2.14.0OSV
  • pydantic-ai-slim, PyPI2.14.1OSV
  • pydantic-ai-slim, PyPI2.15.0OSV
  • pydantic-ai-slim, PyPI2.16.0OSV
  • pydantic-ai-slim, PyPI2.17.0OSV
  • pydantic-ai-slim, PyPI2.18.0OSV
  • pydantic-ai-slim, PyPI2.19.0OSV
  • pydantic-ai-slim, PyPI2.2.0OSV
  • pydantic-ai-slim, PyPI2.20.0OSV
  • pydantic-ai-slim, PyPI2.21.0OSV
  • pydantic-ai-slim, PyPI2.22.0OSV
  • pydantic-ai-slim, PyPI2.23.0OSV
  • pydantic-ai-slim, PyPI2.24.0OSV
  • pydantic-ai-slim, PyPI2.25.0OSV
  • pydantic-ai-slim, PyPI2.26.0OSV
  • pydantic-ai-slim, PyPI2.27.0OSV
  • pydantic-ai-slim, PyPI2.27.1OSV
  • pydantic-ai-slim, PyPI2.3.0OSV
  • pydantic-ai-slim, PyPI2.4.0OSV
  • pydantic-ai-slim, PyPI2.5.0OSV
  • pydantic-ai-slim, PyPI2.5.1OSV
  • pydantic-ai-slim, PyPI2.6.0OSV
  • pydantic-ai-slim, PyPI2.7.0OSV
  • pydantic-ai-slim, PyPI2.8.0OSV
  • pydantic-ai-slim, PyPI2.9.0OSV
  • pydantic-ai-slim, PyPI2.9.1OSV

References 8