CVE-2026-107290
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.
Does this matter?
Lower severity and a low EPSS score (0.51%). Track it; it rarely justifies an emergency change on its own.
Description
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.
- CVSS 3.1
- 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.51% probability · 43th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-1333
- Affected
- pydantic/pydantic ai
- Source
- security-advisories@github.com
EPSS moved from 0.4% on 9 October 2026 to 0.5% on 26 October 2026.
References
- https://github.com/pydantic/pydantic-ai/commit/2faa6181d8a17d83bc9516d035c5270db8730fa0Patch
- https://github.com/pydantic/pydantic-ai/commit/9cdc952e4c3319e85a3e04f2de49fbbb765bd38bPatch
- https://github.com/pydantic/pydantic-ai/commit/a93ea5226be1e93ae13131ae3f22287190411389Patch
- https://github.com/pydantic/pydantic-ai/commit/c3fd1cc1f15fdbf750d78e4e3ec1e8b4d6a3d920Exploit, Patch
- https://github.com/pydantic/pydantic-ai/commit/fb92ccfc3ca2735dab877e2ed73856681bf72ad1Patch
- https://github.com/pydantic/pydantic-ai/pull/8397Patch, Vendor Advisory
- https://github.com/pydantic/pydantic-ai/pull/8399Patch, Vendor Advisory
- https://github.com/pydantic/pydantic-ai/pull/8418Patch, Vendor Advisory
- https://github.com/pydantic/pydantic-ai/pull/84332Broken Link
- https://github.com/pydantic/pydantic-ai/pull/8434Patch, Vendor Advisory
- https://github.com/pydantic/pydantic-ai/releases/tag/v1.107.6Patch, Release Notes, Vendor Advisory
- https://github.com/pydantic/pydantic-ai/releases/tag/v2.44.0Patch, Release Notes, Vendor Advisory
- https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-fpf4-vwcp-v4hpVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.