CVE-2026-23553

LOW

2.9

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.

Details CVE

Score CVSS v3.12.9

SeveriteLOW

Vecteur CVSSCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Vecteur d'attaqueLOCAL

ComplexiteHIGH

Privileges requisNONE

Interaction utilisateurNONE

Publie1/28/2026

Derniere modification2/9/2026

Sourcenvd

Observations honeypot0

Produits affectes

xen:xen

Faiblesses (CWE)

CWE-665CWE-693

References

https://xenbits.xenproject.org/xsa/advisory-479.html(security@xen.org)

http://www.openwall.com/lists/oss-security/2026/01/27/3(af854a3a-2127-422b-91ae-364da2661108)

http://xenbits.xen.org/xsa/advisory-479.html(af854a3a-2127-422b-91ae-364da2661108)

Correlations IOC

Aucune correlation enregistree

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