CVE intelligence and bounded remediation

CVE-2021-30465 — runc before 1.0.0-rc95 allows a Container Filesystem Breakout via Directory Traversal

High CVSS 8.5

runc before 1.0.0-rc95 allows a Container Filesystem Breakout via Directory Traversal. To exploit the vulnerability, an attacker must be able to create multiple containers with a fairly specific mount configuration. The problem occurs via a symlink-exchange attack that relies on a race condition.

Severity
High
CVSS
8.5 (3.1)
Published
2021-05-27
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-362

Affected products

  • linuxfoundation / runc
  • linuxfoundation / runc / 1.0.0

Showing 2 representative product identities from 18 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

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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