CVEvulnerability

CVE-2026-23553

2.9 LOW Published 2026-01-28 Modified 2026-06-17 Official page ↗
Status
Analyzed
Published
2026-01-28
Last modified
2026-06-17
Assigner
[email protected]
CVSS 3.1 (134c704f-9b21-4f2e-91b3-4a467353bcc0)
2.9 LOW — CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Weaknesses
CWE-665, CWE-693

Description

In the context switch logic Xen attempts to skip an IBPB in the case of a vCPU returning to a CPU on which it was the previous vCPU to run. While safe for Xen's isolation between vCPUs, this prevents the guest kernel correctly isolating between tasks. Consider: 1) vCPU runs on CPU A, running task 1. 2) vCPU moves to CPU B, idle gets scheduled on A. Xen skips IBPB. 3) On CPU B, guest kernel switches from task 1 to 2, issuing IBPB. 4) vCPU moves back to CPU A. Xen skips IBPB again. Now, task 2 is running on CPU A with task 1's training still in the BTB.

Affected configurations

• xen xen (>= 4.6.0)

Related

Weakness · CWE (2)

  • CWE-665 Improper Initialization weakness
  • CWE-693 Protection Mechanism Failure weakness

References