Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| pydantic | pydantic-ai | >= 1.77.0, < 1.107.7, >= 2.0.0b1, < 2.52.0 | — |
| pydantic | pydantic-ai-slim | >= 1.77.0, < 1.107.7, >= 2.0.0b1, < 2.52.0 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | pydantic-ai | >= 1.77.0, < 1.107.7 | 1.107.7 | GHSA-v36g-jcw9-x7cw |
| PyPI | pydantic-ai | >= 2.0.0b1, < 2.52.0 | 2.52.0 | GHSA-v36g-jcw9-x7cw |
| PyPI | pydantic-ai | >= 1.77.0, < 1.107.7 · >= 2.0.0b1, < 2.52.0 | 1.107.7, 2.52.0 | PYSEC-2026-4281 |
| PyPI | pydantic-ai-slim | >= 1.77.0, < 1.107.7 | 1.107.7 | GHSA-v36g-jcw9-x7cw |
| PyPI | pydantic-ai-slim | >= 2.0.0b1, < 2.52.0 | 2.52.0 | GHSA-v36g-jcw9-x7cw |
| PyPI | pydantic-ai-slim | >= 1.77.0, < 1.107.7 · >= 2.0.0b1, < 2.52.0 | 1.107.7, 2.52.0 | PYSEC-2026-4290 |
References
- 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/releases/tag/v1.107.7
- https://github.com/pydantic/pydantic-ai/releases/tag/v2.52.0