CVE-2026-107287

Status: AnalyzedMedium (6.5)—

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

Version: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Base score: 6.5

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.28%
Percentile among all scored CVEs: 19
Score date: 10/13/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1203 Exploitation for Client Executionexecution85 %
Primary impactT1499 Endpoint Denial of Serviceimpact90 %

El vector CVSS:3.1 con UI:R (requiere interacción del usuario) y AV:N (red) indica ejecución en cliente. La descripción explícita de consumo excesivo de CPU/memoria en procesamiento de HTML controlado por atacante mediante web_fetch_tool sustenta DoS (T1499).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Filter Network Traffic Application Isolation and Sandboxing Exploit Protection Update Software

Affected technologies (1)

Pydantic — Pydantic AI

CWEs

CWE-400, CWE-407

References

Raw JSON (NVD)

Show

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