CVE-2026-107290: Pydantic AI: Event loop blocked by quadratic title extraction in `web_fetch`
pydantic · pydantic-ai
Affected: pydantic-ai · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 44% of scored CVEs
DescriptionCVE.org
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.
Affected products2
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- pydantic · pydantic-ai>= 1.77.0, < 1.107.6; >= 2.0.0b1, < 2.44.0
- pydantic · pydantic-ai-slim>= 1.77.0, < 1.107.6; >= 2.0.0b1, < 2.44.0
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- pydantic
- Published
- October 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-107290 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.
References
- NVD entrynvd.nist.gov
- CVE recordcve.org
- Weakness CWE-1333cwe.mitre.org
- github.com/pydantic/pydantic-ai/security/advisories/GHSA-fpf4-vwgithub.com
- github.com/pydantic/pydantic-ai/pull/8397github.com
- github.com/pydantic/pydantic-ai/pull/8399github.com
- github.com/pydantic/pydantic-ai/pull/8418github.com
- github.com/pydantic/pydantic-ai/pull/84332github.com
- github.com/pydantic/pydantic-ai/pull/8434github.com
- github.com/pydantic/pydantic-ai/commit/2faa6181d8a17d83bc9516d03github.com
- github.com/pydantic/pydantic-ai/commit/9cdc952e4c3319e85a3e04f2dgithub.com
- github.com/pydantic/pydantic-ai/commit/a93ea5226be1e93ae13131ae3github.com
- github.com/pydantic/pydantic-ai/commit/c3fd1cc1f15fdbf750d78e4e3github.com
- github.com/pydantic/pydantic-ai/commit/fb92ccfc3ca2735dab877e2edgithub.com
- github.com/pydantic/pydantic-ai/releases/tag/v1.107.6github.com
1 more reference is in the CVE record.