VDB
DEBIAN-CVE-2026-23553
DEBIAN-CVE-2026-23553
PUBLISHED
CVSS 2.9000000953674316 LOW
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.
Risk Scores
CVSS 3.1
2.9000000953674316
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Debian:14 | xen | 4.20.0+68-g35cb38b222-1, 4.20.2+7-g1badcf5035-1, 4.20.2+7-g1badcf5035-2 |
| Debian:13 | xen | 4.20.2+7, 4.20.2+7, 0 |
| Debian:12 | xen | 4.17.3+10, 4.17.3+36, 4.17.5+23 |
| Debian:11 | xen | 4.17.2+55, 4.17.2+76, 4.17.2+76 |
Timeline
- Jan 28, 2026 CVE Published
- Apr 28, 2026 CVE Updated