CVE intelligence and bounded remediation

CVE-2021-20315 — Gnome Gnome-Shell security vulnerability

Medium CVSS 6.1

A locking protection bypass flaw was found in some versions of gnome-shell as shipped within CentOS Stream 8, when the "Application menu" or "Window list" GNOME extensions are enabled. This flaw allows a physical attacker who has access to a locked system to kill existing applications and start new ones as the locked user, even if the session is still locked.

Severity
Medium
CVSS
6.1 (3.1)
Published
2022-02-18
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-667

Affected products

  • gnome / gnome-shell
  • centos / stream / 8

Matched remediation archetype

Race condition, TOCTOU, and lifecycle synchronization

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Check exposure

  • Map concurrent actors, shared state, lock boundaries, signals, callbacks, retries, and check-then-use sequences in the affected path.
  • Determine whether untrusted users can influence timing, object names, filesystem state, or repeated state transitions.
  • Identify clustered and multi-process behavior that repository-local tests may not represent.

Remediate safely

  • Make the sensitive state transition atomic or protect it with a consistently ordered synchronization primitive.
  • Perform authorization and invariant checks on the same authoritative object and transaction used for the operation.
  • Use unique private resources, safe ownership transfer, and idempotent operations; add deterministic concurrency regression tests.

Authoritative sources

Complete CVE record and remediation plan

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