Pydantic AI: Excessive resource use when local web fetching converts nested HTML

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-107287
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-08 16:17:03 UTC
Updated2026-10-08 16:17:03 UTC
DescriptionPydantic 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.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Problem Types: CWE-400 | CWE-407 | CWE-400 CWE-400: Uncontrolled Resource Consumption | CWE-407 CWE-407: Inefficient Algorithmic Complexity

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
3.1CNADECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Pydantic Pydantic-ai affected >= 1.77.0, < 1.107.7 Not specified
CNA Pydantic Pydantic-ai affected >= 2.0.0b1, < 2.52.0 Not specified
CNA Pydantic Pydantic-ai-slim affected >= 1.77.0, < 1.107.7 Not specified
CNA Pydantic Pydantic-ai-slim affected >= 2.0.0b1, < 2.52.0 Not specified

References

ReferenceSourceLinkTags
github.com/pydantic/pydantic-ai/commit/2fd38792693da00a3ca5412aeffb43678... [email protected] github.com
github.com/pydantic/pydantic-ai/pull/8985 [email protected] github.com
github.com/pydantic/pydantic-ai/releases/tag/v1.107.7 [email protected] github.com
github.com/pydantic/pydantic-ai/commit/2b247add4950bef61d352e7ca8aefbd20... [email protected] github.com
github.com/pydantic/pydantic-ai/releases/tag/v2.52.0 [email protected] github.com
github.com/pydantic/pydantic-ai/pull/8984 [email protected] github.com
github.com/pydantic/pydantic-ai/security/advisories/GHSA-v36g-jcw9-x7cw [email protected] github.com
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