GHSA-v36g-jcw9-x7cw Pydantic AI: Excessive resource use when local web fetching converts nested HTML

• PyPI pydantic-ai: >= 1.77.0, < 1.107.7 → fixed in 1.107.7 • PyPI pydantic-ai: >= 2.0.0b1, < 2.52.0 → fixed in 2.52.0 • PyPI pydantic-ai-slim: >= 1.77.0, < 1.107.7 → fixed in 1.107.7 • PyPI pydantic-ai-slim: >= 2.0.0b1, < 2.52.0 → fixed in 2.52.0

Summary Applications using Pydantic AI's local web-fetch tool can experience excessive CPU and memory use when it converts attacker-controlled HTML. An agent must fetch the affected page; provider-native web fetching is not affected. Details Nested block elements cause HTML-to-Markdown conversion to reprocess accumulated text at each level and can greatly expand the intermediate output. The response-body limit bounds downloaded bytes, while the returned-content limit is applied only after conversion. On current releases, conversion runs in a worker thread but can still consume substantial resources and delay other work in the process. Older releases performed conversion on the event loop. Mitigation Upgrade to a patched release of `pydantic-ai` or `pydantic-ai-slim`. If you cannot upgrade yet, avoid using local web fetching for attacker-controlled HTML.