2.9

CVE-2026-23553

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.
Verknüpft mit AI von unstrukturierten Daten zu bestehenden CPE der NVD
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Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Xen ≫ Xen HwPlatformx86 Version >= 4.6.0
Zu dieser CVE wurde keine CISA KEV oder CERT.AT-Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.03% 0.069
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
134c704f-9b21-4f2e-91b3-4a467353bcc0 2.9 1.4 1.4
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
CWE-665 Improper Initialization

The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.

CWE-693 Protection Mechanism Failure

The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.

http://www.openwall.com/lists/oss-security/2026/01/27/3
Patch
Third Party Advisory
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Mitigation
http://xenbits.xen.org/xsa/advisory-479.html
Patch
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