CVE-2026-23553

LOW
2026-01-28 [email protected]
2.9
CVSS 3.1

CVSS Vector

CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack Vector
Local
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

Lifecycle Timeline

3
Analysis Generated
Mar 12, 2026 - 21:54 vuln.today
Patch Released
Feb 09, 2026 - 18:46 nvd
Patch available
CVE Published
Jan 28, 2026 - 16:16 nvd
LOW 2.9

Tags

Linux

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.

Analysis

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. …

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Remediation

During next maintenance window: Apply vendor patches when convenient. Vendor patch is available.

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Priority Score

15
Low Medium High Critical
KEV: 0
EPSS: +0.0
CVSS: +14
POC: 0

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CVE-2026-23553 vulnerability details – vuln.today
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