CVE-2026-107287mediumCWE-400CWE-407

CVE-2026-107287: medium-severity vulnerability in pydantic-ai

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

Published · Updated

Follow this CVE+ Monitor pydantic-ai+ Monitor pydantic-ai-slim

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 6.5epss 0.3%
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:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Affected products
pydantic · pydantic-aipydantic · pydantic-ai-slim
Related CVEs — pydantic-ai

In the same product, most dangerous first.

CVE-2026-25580HIGHPydantic AI Affected by Server-Side Request Forgery (SSRF) in URL Download HandlingEPSS 0.6%CVE-2026-107291LOWPydantic AI OpenTelemetry instrumentation: exception events on tool and agent run spans include content when `include_content=False`EPSS 0.6%CVE-2026-107290MEDIUMPydantic AI: Event loop blocked by quadratic title extraction in `web_fetch`EPSS 0.5%CVE-2026-107286HIGHPydantic AI: Concurrency-limited models can keep their slot when a streamed request ends earlyEPSS 0.4%CVE-2026-107294MEDIUMPydantic AI: Unbounded memory use when downloading remote content via web_fetch or FileUrlEPSS 0.4%CVE-2026-48782MEDIUMpydantic-ai: SSRF blocklist bypass via IPv4-compatible, SIIT/IVI, and local NAT64 IPv6 addresses (incomplete fix of CVE-2026-46678)EPSS 0.4%