Medium 6.5Published Oct 8, 2026

CVE-2026-107287Pydantic AI: Excessive resource use when local web fetching converts nested HTML

Updated under an hour ago (Oct 28, 2026, 10:00 AM ET)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for pydantic-ai

Exploited in the last 30 days

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.

CVSS: 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-400, CWE-407
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Oct 13, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

pydantic pydantic-ai pydantic:ai (from the name)	from 1.77.0, < 1.107.7; from 2.0.0b1, < 2.52.0	CNA record
pydantic pydantic-ai-slim pydantic:ai_slim (from the name)	from 1.77.0, < 1.107.7; from 2.0.0b1, < 2.52.0	CNA record
pydantic pydantic_ai pydantic:pydantic_ai	from 1.77.0 before 1.107.7; from 2.0.0 before 2.52.0	NVD

References

References

https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-v36g-jcw9-x7cw	x-refsource-confirm, vendor-advisory
https://github.com/pydantic/pydantic-ai/pull/8984	x-refsource-misc, patch, vendor-advisory
https://github.com/pydantic/pydantic-ai/pull/8985	x-refsource-misc, patch, vendor-advisory
https://github.com/pydantic/pydantic-ai/commit/2b247add4950bef61d352e7ca8aefbd20539180c	x-refsource-misc, patch
https://github.com/pydantic/pydantic-ai/commit/2fd38792693da00a3ca5412aeffb436787af3545	x-refsource-misc, patch
https://github.com/pydantic/pydantic-ai/releases/tag/v1.107.7	x-refsource-misc, patch, release-notes, vendor-advisory
https://github.com/pydantic/pydantic-ai/releases/tag/v2.52.0	x-refsource-misc, patch, release-notes, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.