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ALPINE-CVE-2026-23553

LowCVSS 2.9 / 10
Published Jan 28, 2026·Last modified Jan 29, 2026
Affected Components(0)

No affected components available

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.

Risk Scores
Base Score
2.9

The vulnerability requires local access to the device to be exploited. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information.

Threat Intelligence
2.7

Limited exploitation activity has been observed. Close monitoring and planned remediation are recommended.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

Related Vulnerabilities
  • CVE-2026-23553
    Upstream
  • EUVD-2026-4882
    Upstream

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