---
id: CVE-2026-63349
title: >-
  AnyIO is a high level asynchronous concurrency and networking framework that
  works on top of either Trio or asyncio
summary: >-
  AnyIO is a high level asynchronous concurrency and networking framework that
  works on top of either Trio or asyncio. In 4.14.0, AnyIO accepts the POSIX
  extra_groups argument in anyio.run_process() and anyio.open_process(), but
  open_proce…
severity: high
cvss: 7
cvssVector: 'CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'
cwe:
  - CWE-266
  - CWE-269
  - CWE-648
vendor: agronholm
product: anyio
affected:
  - 'anyio >= 4.14.0, < 4.14.2'
patched:
  - anyio 4.14.2
published: '2026-09-18'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T14:10:13.927'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63349'
references:
  - url: >-
      https://github.com/agronholm/anyio/commit/eb562e6462ee46b1904e50b02ce00a858cdeb200
    label: security-advisories@github.com
  - url: 'https://github.com/agronholm/anyio/pull/1209'
    label: security-advisories@github.com
  - url: 'https://github.com/agronholm/anyio/releases/tag/4.14.2'
    label: security-advisories@github.com
  - url: 'https://github.com/agronholm/anyio/security/advisories/GHSA-3w57-8xmc-8v26'
    label: security-advisories@github.com
  - url: 'https://github.com/advisories/GHSA-3w57-8xmc-8v26'
  - url: 'https://github.com/agronholm/anyio'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63349.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-63349'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2537927'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-63349'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63349'
tags:
  - nvd
  - cve.org
  - ghsa
  - pip
  - osv
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00108
epssPercentile: 0.01092
aliases:
  - GHSA-3w57-8xmc-8v26
ecosystem: pip
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-24T21:00:28.848164Z'
cvssSource: cna
ingestedAt: '2026-09-18T17:46:41.521Z'
scores:
  cna: 7
  vendor: 4.4
---

## Overview

AnyIO is a high level asynchronous concurrency and networking framework that works on top of either Trio or asyncio. In 4.14.0, AnyIO accepts the POSIX extra_groups argument in anyio.run_process() and anyio.open_process(), but open_process() forwards the group argument to the backend instead of extra_groups. A caller that supplies extra_groups=[] to clear inherited supplementary groups can therefore launch a child that retains the parent process groups, undermining a privilege-dropping boundary. If group is also supplied, the integer group value is passed where an iterable of supplementary groups is expected and the launch can fail with TypeError. This issue affects POSIX applications that rely on AnyIO subprocess helpers to launch less-privileged child processes. This issue is fixed in version 4.14.2.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-63349)

Affected packages:

- `anyio >= 4.14.0, < 4.14.2`

Patched in:

- `anyio 4.14.2`

Source: https://github.com/advisories/GHSA-3w57-8xmc-8v26

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Ansible Automation Orchestrator 2026, Confidential Compute Attestation, Exploit Intelligence, Lightspeed Core, Migration Toolkit for Applications 8, Migration Toolkit for Containers, … · no fix planned: Exploit Intelligence, Red Hat Ansible Automation Platform 2, Ansible Automation Orchestrator 2026, Confidential Compute Attestation, … · updated 2026-09-25 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63349.json)