CVE-2026-107290

Status: AnalyzedMedium (6.5)—

Pydantic AI is a Python agent framework for building applications and workflows with Generative AI. From 1.77.0 until 1.107.6 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.

CVSS

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

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.42%
Percentile among all scored CVEs: 34
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.

ExploitationT1210 Exploitation of Remote Serviceslateral movement72 %
Primary impactT1499.004 Application or System Exploitationimpact85 %
Secondary impactT1499 Endpoint Denial of Serviceimpact78 %

AV:N, PR:L sin UI indica acceso de red con privilegios mínimos (T1210). El atacante entrega una página malformada que bloquea el event loop (DoS/T1499.004) por extracción cuadrática de títulos y anidamiento excesivo.

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 Vulnerability Scanning Threat Intelligence Program Privileged Account Management Network Segmentation Disable or Remove Feature or Program

Affected technologies (1)

Pydantic — Pydantic AI

CWEs

CWE-1333

References

Raw JSON (NVD)

Show

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