CVE-2026-23553: fallo de gravedad baja en Xen
x86: incomplete IBPB for vCPU isolation
Publicada el
Aviso por correo cuando entre en el KEV, tenga PoC pública o suba de nota.
8Vexday Risk Score
Sin señal de explotación. Ningún artefacto público de explotación conocido hasta ahora.
ssvc Trackcvss 2.9epss 0.1%
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.
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Productos afectados
Xen · XenCVEs relacionadas — Xen
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