Disclosure summary
Pydantic AI is a Python agent framework for building applications and workflows with Generative AI. From 1.77.0 until 1.107.7 and 2.52.0, the local web_fetch_tool and the WebFetch local fallback can consume excessive CPU and memory during HTML-to-Markdown conversion of attacker-controlled HTML containing deeply nested block elements. Conversion repeatedly reprocesses accumulated text and can greatly expand intermediate output before the returned-content limit is applied, allowing a model-directed fetch to delay other work in the process. Provider-native web fetching is not affected. This issue is fixed in versions 1.107.7 and 2.52.0.
Source-reported weakness categories
CWE-400, CWE-407
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
NIST National Vulnerability Database · NVD-CVE-2026-107287
Open original source · Updated Oct 08, 2026
Only CPE matches marked vulnerable=true are indexed. AND/OR platform conditions must be checked in the original NVD record.
GitHub Reviewed Security Advisories · GHSA-v36g-jcw9-x7cw
Open original source · Updated Oct 08, 2026
Pydantic AI: Excessive resource use when local web fetching converts nested HTML
Source severity: MEDIUM / 0
| Ecosystem | Package | Affected range | First patched |
|---|---|---|---|
| pip | pydantic-ai | >= 1.77.0, < 1.107.7 | 1.107.7 |
| pip | pydantic-ai | >= 2.0.0b1, < 2.52.0 | 2.52.0 |
| pip | pydantic-ai-slim | >= 1.77.0, < 1.107.7 | 1.107.7 |
| pip | pydantic-ai-slim | >= 2.0.0b1, < 2.52.0 | 2.52.0 |
Original records & references
- NIST NVD record
- CVE Program record
- github.com
- github.com
- github.com
- github.com
- github.com
- github.com
- github.com
PUBLISHED 2026-10-08T12:17:03-04:00
MODIFIED 2026-10-08T17:05:00-04:00
INGESTED 2026-10-10T20:55:03-04:00