CVE-2026-107290

Pydantic AI is a Python agent framework for building applications and workflows with Generative AI. From 1.77.0 until 1.107.6 and 2.44.0, the local web_fetch_tool and the WebFetch local fallback process server-controlled responses with quadratic title extraction, whitespace normalization, and ordered-list numbering. An attacker-controlled page of modest size can therefore block the event loop for an extended period, stalling other agent runs and requests, while unsupported codecs or excessive HTML or JSON nesting can abort an individual run. This issue is fixed in versions 1.107.6 and 2.44.0.

• CWE-1333

• https://github.com/pydantic/pydantic-ai/commit/2faa6181d8a17d83bc9516d035c5270db8730fa0
• https://github.com/pydantic/pydantic-ai/commit/9cdc952e4c3319e85a3e04f2de49fbbb765bd38b
• https://github.com/pydantic/pydantic-ai/commit/a93ea5226be1e93ae13131ae3f22287190411389
• https://github.com/pydantic/pydantic-ai/commit/c3fd1cc1f15fdbf750d78e4e3ec1e8b4d6a3d920
• https://github.com/pydantic/pydantic-ai/commit/fb92ccfc3ca2735dab877e2ed73856681bf72ad1
• https://github.com/pydantic/pydantic-ai/pull/8397
• https://github.com/pydantic/pydantic-ai/pull/8399
• https://github.com/pydantic/pydantic-ai/pull/8418
• https://github.com/pydantic/pydantic-ai/pull/84332
• https://github.com/pydantic/pydantic-ai/pull/8434
• https://github.com/pydantic/pydantic-ai/releases/tag/v1.107.6
• https://github.com/pydantic/pydantic-ai/releases/tag/v2.44.0
• https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-fpf4-vwcp-v4hp

Published

Oct 8, 2026

Last Modified

Oct 8, 2026

Status

Awaiting Analysis

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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