# Pydantic AI: Excessive resource use when local web fetching converts nested HTML

Advisory record · `GHSA-v36g-jcw9-x7cw`

- **Identifiers:** `GHSA-v36g-jcw9-x7cw` · `CVE-2026-107287` · `PYSEC-2026-4281` · `PYSEC-2026-4290`
- **State:** Confirmed
- **Severity:** CVSS 6.5 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-400](https://cwe.mitre.org/data/definitions/400.html) · [CWE-407](https://cwe.mitre.org/data/definitions/407.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 8 Oct 2026
- **Updated:** 15 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 8 Oct 2026, 17:40 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `pydantic-ai` (PyPI): affected `>=1.77.0, <1.107.7 || >=2.0.0b1, <2.52.0`; fixed in `1.107.7`, `2.52.0`
- `pydantic-ai-slim` (PyPI): affected `>=1.77.0, <1.107.7 || >=2.0.0b1, <2.52.0`; fixed in `1.107.7`, `2.52.0`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Pydantic AI (packages pydantic-ai and pydantic-ai-slim) versions 1.77.0 up to 1.107.7 and 2.0.0b1 up to 2.52.0 are affected. When an agent's local web-fetch tool converts attacker-controlled nested HTML, the conversion can consume excessive CPU and memory and delay other work in the process. Upgrade to pydantic-ai or pydantic-ai-slim 1.107.7 or 2.52.0. If you cannot upgrade, avoid local web fetching of attacker-controlled HTML.

Written 1 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 6.5 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0028, the 20th percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:08 UTC: First seen by agentprime
- 31 Oct 2026, 14:08 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-v36g-jcw9-x7cw)

## Sources

- [GitHub Advisory Database: GHSA-v36g-jcw9-x7cw](https://github.com/advisories/GHSA-v36g-jcw9-x7cw)
- [OSV: GHSA-v36g-jcw9-x7cw](https://osv.dev/vulnerability/GHSA-v36g-jcw9-x7cw)
- <https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-v36g-jcw9-x7cw>
- <https://github.com/pydantic/pydantic-ai/pull/8984>
- <https://github.com/pydantic/pydantic-ai/pull/8985>
- <https://github.com/pydantic/pydantic-ai/commit/2b247add4950bef61d352e7ca8aefbd20539180c>
- <https://github.com/pydantic/pydantic-ai/commit/2fd38792693da00a3ca5412aeffb436787af3545>
- <https://github.com/pydantic/pydantic-ai>
- <https://github.com/pydantic/pydantic-ai/releases/tag/v1.107.7>
- <https://github.com/pydantic/pydantic-ai/releases/tag/v2.52.0>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-v36g-jcw9-x7cw>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-v36g-jcw9-x7cw/>. Everything for agents: <https://agentprime.io/llms.txt>.