CVE-2026-63349
highpriority · track · 0EPSS 0.001 · 1 %ileFRUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–high · 3.7–7
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
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affected products (1)
Products and version ranges known to be affected.
advisories (3)
Vendor and ecosystem advisories describing this.
- GHSA-3w57-8xmc-8v26AnyIO run_process/open_process ignores extra_groups and can retain parent supplementary groups2026-09-18ghsa · osvUS
AnyIO 4.14.0 accepts the POSIX extra_groups argument on anyio.run_process() and anyio.open_process(), but open_process() forwards the wrong variable to the backend: when extra_groups is not None, it assigns kwargs["extra_groups"] = group instead of extra_groups. As a result, callers cannot reliably clear or set supplementary groups for child processes. In a disposable Linux container, Python's subprocess.run(..., extra_groups=[]) clears a synthetic parent supplementary group list, while anyio.run_process(..., extra_groups=[]) preserves the parent groups. If group is also supplied, AnyIO passes an integer as extra_groups and the call fails with TypeError. This is a POSIX privilege-dropping correctness issue for applications that rely on AnyIO subprocess helpers to launch less-privileged child processes.
- CERTFR-2026-AVI-1385Multiples vulnérabilités dans les produits VMwareFrançais2026-10-26vendor · certfrFR
- PYSEC-2026-4023AnyIO run_process/open_process ignores extra_groups and can retain parent supplementary groups2026-10-01vendor · osvUS
AnyIO 4.14.0 accepts the POSIX extra_groups argument on anyio.run_process() and anyio.open_process(), but open_process() forwards the wrong variable to the backend: when extra_groups is not None, it assigns kwargs["extra_groups"] = group instead of extra_groups. As a result, callers cannot reliably clear or set supplementary groups for child processes. In a disposable Linux container, Python's subprocess.run(..., extra_groups=[]) clears a synthetic parent supplementary group list, while anyio.run_process(..., extra_groups=[]) preserves the parent groups. If group is also supplied, AnyIO passes an integer as extra_groups and the call fails with TypeError. This is a POSIX privilege-dropping correctness issue for applications that rely on AnyIO subprocess helpers to launch less-privileged child processes.
also known as (2)
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sources
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references (4) nvd
External citations — patches, advisories, analysis.
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