CVE intelligence and bounded remediation

CVE-2022-26362 — x86 pv: Race condition in typeref acquisition Xen maintains a type reference count for pages, in addition to a regular reference count

Medium CVSS 6.9

x86 pv: Race condition in typeref acquisition Xen maintains a type reference count for pages, in addition to a regular reference count. This scheme is used to maintain invariants required for Xen's safety, e.g. PV guests may not have direct writeable access to pagetables; updates need auditing by Xen. Unfortunately, the logic for acquiring a type reference has a race condition, whereby a safely TLB flush is issued too early and creates a window where the guest can re-establish the read/write mapping before writeability is prohibited.

Severity
Medium
CVSS
6.9 (2.0)
Published
2022-06-09
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-362

Affected products

  • xen / xen
  • fedoraproject / fedora / 35
  • fedoraproject / fedora / 36
  • debian / debian_linux / 11.0

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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