Read the docs
TI-2026-69608 Aliases CVE-2026-107290GHSA-fpf4-vwcp-v4hp

Pydantic AI: Event loop blocked by quadratic title extraction in web_fetch

Priority LOW 29CWE-1333Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 2 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-1333.

Summary

Pydantic AI, a Python agent framework for Generative AI applications, has quadratic-time title extraction, whitespace normalization and ordered-list numbering in the local web_fetch_tool and the WebFetch local fallback. From 1.77.0 before 1.107.6, and from 2.0.0b1 before 2.44.0, an attacker-controlled page of modest size can block the event loop for an extended period, stalling other agent runs and requests. Unsupported codecs or excessive HTML or JSON nesting can abort an individual run. CVSS 3.1 scores this 6.5 (MEDIUM), with CWE-1333 and CWE-407.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00512 43rd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial pydantic-ai (pydantic): 1.107.6, 2.44.0pydantic-ai-slim (pydantic): 1.107.6, 2.44.0+2 more productsRed Hat: 2 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
pydanticpydantic-ai1.77.0 to before 1.107.6; 2.0.0b1 to before 2.44.01.107.6, 2.44.0Patch availableCNA
pydanticpydantic-ai-slim1.77.0 to before 1.107.6; 2.0.0b1 to before 2.44.01.107.6, 2.44.0Patch availableCNA
—pydantic-ai (PyPI)1.77.0 to before 1.107.61.107.6Patch availableGHSA-fpf4-vwcp-v4hp
—pydantic-ai (PyPI)2.0.0b1 to before 2.44.02.44.0Patch availableGHSA-fpf4-vwcp-v4hp
—pydantic-ai-slim (PyPI)1.77.0 to before 1.107.61.107.6Patch availableGHSA-fpf4-vwcp-v4hp
—pydantic-ai-slim (PyPI)2.0.0b1 to before 2.44.02.44.0Patch availableGHSA-fpf4-vwcp-v4hp
  • pydantic-ai Vendorpydantic Affected 1.77.0 to before 1.107.6; 2.0.0b1 to before 2.44.0 Fixed in 1.107.6, 2.44.0 Patch available CNA
  • pydantic-ai-slim Vendorpydantic Affected 1.77.0 to before 1.107.6; 2.0.0b1 to before 2.44.0 Fixed in 1.107.6, 2.44.0 Patch available CNA
  • pydantic-ai (PyPI) Vendor— Affected 1.77.0 to before 1.107.6 Fixed in 1.107.6 Patch available GHSA-fpf4-vwcp-v4hp
  • pydantic-ai (PyPI) Vendor— Affected 2.0.0b1 to before 2.44.0 Fixed in 2.44.0 Patch available GHSA-fpf4-vwcp-v4hp
  • pydantic-ai-slim (PyPI) Vendor— Affected 1.77.0 to before 1.107.6 Fixed in 1.107.6 Patch available GHSA-fpf4-vwcp-v4hp
  • pydantic-ai-slim (PyPI) Vendor— Affected 2.0.0b1 to before 2.44.0 Fixed in 2.44.0 Patch available GHSA-fpf4-vwcp-v4hp

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:pydantic:pydantic_ai:*:*:*:*:*:python:*:*1.77.0 to before 1.107.6Vulnerablepydantic
cpe:2.3:a:pydantic:pydantic_ai:*:-:*:*:*:python:*:*2.0.0 to before 2.44.0Vulnerablepydantic
  • cpe:2.3:a:pydantic:pydantic_ai:*:*:*:*:*:python:*:* Versions 1.77.0 to before 1.107.6 Vulnerable ·pydantic
  • cpe:2.3:a:pydantic:pydantic_ai:*:-:*:*:*:python:*:* Versions 2.0.0 to before 2.44.0 Vulnerable ·pydantic

Remediation

Upgrade pydantic-ai and pydantic-ai-slim to 1.107.6 or 2.44.0. Red Hat rates this Moderate; Lightspeed Core and RHEL AI 3 have no fix available yet.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

  • Fix · CNA pydantic-ai (pydantic) Fixed in 1.107.6, 2.44.0
  • Fix · CNA pydantic-ai-slim (pydantic) Fixed in 1.107.6, 2.44.0
  • Fix · GHSA-fpf4-vwcp-v4hp pydantic-ai (PyPI) Fixed in 1.107.6 Advisory →
  • Fix · GHSA-fpf4-vwcp-v4hp pydantic-ai (PyPI) Fixed in 2.44.0 Advisory →
  • Fix · GHSA-fpf4-vwcp-v4hp pydantic-ai-slim (PyPI) Fixed in 1.107.6 Advisory →
  • Fix · GHSA-fpf4-vwcp-v4hp pydantic-ai-slim (PyPI) Fixed in 2.44.0 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Lightspeed CoreAffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux AI (RHEL AI) 3AffectedNo fix yet: Fix deferred

Timeline

  1. 2026-10-08 Threatist record created from CVE-2026-107290
  2. 2026-10-08 Alias added: GHSA-fpf4-vwcp-v4hp
  3. 2026-10-09 Affected versions changed · Red Hat
  4. 2026-10-09 CVSS score added · Red Hat
  5. 2026-10-10 CISA SSVC decision points changed
  6. 2026-10-10 Priority changed: MEDIUM → LOW

References

Exploit 1

Patch 10

Advisory 1

Other 3

  • TI-2026-20687 Pydantic AI Affected by Server-Side Request Forgery (SSRF) in URL Download Handling CVSS 3.1HIGH 8.6
  • TI-2026-69551 Pydantic AI keeps concurrency slots after streams end early CVSS 3.1HIGH 7.5
  • TI-2026-46990 Incorrect authorization in pydantic-ai CVSS 3.1MEDIUM 6.5
  • TI-2026-69610 Cross-site requests run agent tools in pydantic-ai web chat CVSS 3.1HIGH 7.6
  • TI-2026-20740 Pydantic AI affected by Stored XSS via Path Traversal in Web UI CDN URL CVSS 3.1HIGH 7.1
  • TI-2026-69617 Pydantic AI blocklist bypass via IPv6 zone identifier allows SSRF CVSS 3.1MEDIUM 6.8
See all 15 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences