CVE-2026-107287: Pydantic AI Remote Code Execution Vulnerability

MODERATE
Advisory Identifier: GHSA-v36g-jcw9-x7cw
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CVSS 6.5
CWE-400 CWE-407
Published
Advisory Summary

CVE-2026-107287 is a MODERATE (CVSS 6.5) remote code execution vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Pydantic AI libraries in the PyPI ecosystem. The issue involves excessive resource use when local web fetching converts nested html. Remediation is available by upgrading affected packages to version 1.107.7, 2.52.0.

CVE-2026-107287 at a Glance

CVE Identifier CVE-2026-107287
GHSA Identifier GHSA-v36g-jcw9-x7cw
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product Pydantic AI
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-107287

To remediate this vulnerability, upgrade all affected Pydantic AI dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

pydantic-ai fixed: 1.107.7 
pip install pydantic-ai>=1.107.7
pydantic-ai fixed: 2.52.0 
pip install pydantic-ai>=2.52.0
pydantic-ai-slim fixed: 1.107.7 
pip install pydantic-ai-slim>=1.107.7
pydantic-ai-slim fixed: 2.52.0 
pip install pydantic-ai-slim>=2.52.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show pydantic-ai

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-107287, inspect your installed packages using pip:

pip show pydantic-ai

Analyze the terminal output to locate any version of Pydantic AI in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.107.7), your application is affected.

Note: The pip show pydantic-ai command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. In Pydantic AI, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary Applications using Pydantic AI's local web-fetch tool can experience excessive CPU and memory use when it converts attacker-controlled HTML. An agent must fetch the affected page; provider-native web fetching is not affected. ### Details Nested block elements cause HTML-to-Markdown conversion to reprocess accumulated text at each level and can greatly expand the intermediate output. The response-body limit bounds downloaded bytes, while the returned-content limit is applied only after conversion. On current releases, conversion runs in a worker thread but can still consume substantial resources and delay other work in the process. Older releases performed conversion on the event loop. ### Mitigation Upgrade to a patched release of `pydantic-ai` or `pydantic-ai-slim`. If you cannot upgrade yet, avoid using local web fetching for attacker-controlled HTML.

CVE-2026-107287 Affected Pydantic AI Versions

4 component(s)
Fixed Versions:
1.107.72.52.0
Product / Package Ecosystem Affected Versions Fixed Version
pydantic-ai
pypi/pydantic-ai
PyPI
≥ 1.77.0
< 1.107.7
1.107.7
pydantic-ai
pypi/pydantic-ai
PyPI
≥ 2.0.0b1
< 2.52.0
2.52.0
pydantic-ai-slim
pypi/pydantic-ai-slim
PyPI
≥ 1.77.0
< 1.107.7
1.107.7
pydantic-ai-slim
pypi/pydantic-ai-slim
PyPI
≥ 2.0.0b1
< 2.52.0
2.52.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-v36g-jcw9-x7cw
Pydantic AI Source Repository REPOSITORY
https://github.com/pydantic/pydantic-ai/pull/8984
Pydantic AI Source Repository REPOSITORY
https://github.com/pydantic/pydantic-ai/pull/8985
Security Fix Commit FIX COMMIT
https://github.com/pydantic/pydantic-ai/commit/2b247add4950bef61d352e7ca8aefbd20539180c
Security Fix Commit FIX COMMIT
https://github.com/pydantic/pydantic-ai/commit/2fd38792693da00a3ca5412aeffb436787af3545
Pydantic AI Source Repository REPOSITORY
https://github.com/pydantic/pydantic-ai
Pydantic AI Release RELEASE
https://github.com/pydantic/pydantic-ai/releases/tag/v1.107.7
Pydantic AI Release RELEASE
https://github.com/pydantic/pydantic-ai/releases/tag/v2.52.0

Frequently Asked Questions

What is CVE-2026-107287?
CVE-2026-107287 is a security vulnerability in Pydantic AI involving Excessive resource use when local web fetching converts nested HTML under CWE-400: Uncontrolled Resource Consumption.
Which Pydantic AI versions are affected?
Affected versions include releases prior to 1.107.7, 2.52.0 across affected packages: pydantic-ai, pydantic-ai-slim.
What version fixes CVE-2026-107287?
Upgrading to 1.107.7, 2.52.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is pydantic-ai affected?
Yes, pydantic-ai is affected in releases prior to 1.107.7, 2.52.0. Upgrade your dependency to 1.107.7, 2.52.0 or later.
Is pydantic-ai-slim affected?
Yes, pydantic-ai-slim is affected in releases prior to 1.107.7, 2.52.0. Upgrade your dependency to 1.107.7, 2.52.0 or later.
What is the CVSS score of CVE-2026-107287?
CVE-2026-107287 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-107287?
CVE-2026-107287 is classified under CWE-400: Uncontrolled Resource Consumption (The product does not properly control the allocation and maintenance of a limited resource.).
How can I check PyPI dependencies for CVE-2026-107287?
Run the dependency tree command: 'pip show pydantic-ai'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-v36g-jcw9-x7cw",
  "modified" : "2026-10-08T17:40:50Z",
  "published" : "2026-10-08T17:40:50Z",
  "aliases" : [ "CVE-2026-107287" ],
  "summary" : "Pydantic AI: Excessive resource use when local web fetching converts nested HTML",
  "details" : "### Summary\n\nApplications using Pydantic AI's local web-fetch tool can experience excessive CPU and memory use when it converts attacker-controlled HTML. An agent must fetch the affected page; provider-native web fetching is not affected.\n\n### Details\n\nNested block elements cause HTML-to-Markdown conversion to reprocess accumulated text at each level and can greatly expand the intermediate output. The response-body limit bounds downloaded bytes, while the returned-content limit is applied only after conversion. On current releases, conversion runs in a worker thread but can still consume substantial resources and delay other work in the process. Older releases performed conversion on the event loop.\n\n### Mitigation\n\nUpgrade to a patched release of `pydantic-ai` or `pydantic-ai-slim`. If you cannot upgrade yet, avoid using local web fetching for attacker-controlled HTML.",
  "severity" : [ {
    "type" : "CVSS_V3",
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  "references" : [ {
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  }, {
    "type" : "WEB",
    "url" : "https://github.com/pydantic/pydantic-ai/pull/8984"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pydantic/pydantic-ai/pull/8985"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pydantic/pydantic-ai/commit/2b247add4950bef61d352e7ca8aefbd20539180c"
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    "url" : "https://github.com/pydantic/pydantic-ai/commit/2fd38792693da00a3ca5412aeffb436787af3545"
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    "type" : "PACKAGE",
    "url" : "https://github.com/pydantic/pydantic-ai"
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    "url" : "https://github.com/pydantic/pydantic-ai/releases/tag/v2.52.0"
  } ],
  "database_specific" : {
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    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-08T17:40:50Z",
    "nvd_published_at" : null
  }
}