CVE-2026-23553
- Source
- https://cve.org/CVERecord?id=CVE-2026-23553
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23553.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-23553
- Downstream
- Related
- Published
- 2026-01-28T16:16:16Z
- Modified
- 2026-04-16T04:34:14Z
- Severity
-
- 2.9 (Low) CVSS_V3 - CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N CVSS Calculator
- Summary
- [none]
- Details
-
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:
- vCPU runs on CPU A, running task 1.
- vCPU moves to CPU B, idle gets scheduled on A. Xen skips IBPB.
- On CPU B, guest kernel switches from task 1 to 2, issuing IBPB.
- 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.
- References