Is CVE-2026-23553 actively exploited?

CVE-2026-23553 has no public evidence of in-the-wild exploitation as of 2026-02-09.

What is the CVSS score for CVE-2026-23553?

CVE-2026-23553 has a CVSS score of 2.9 (LOW severity). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N.

How do I patch CVE-2026-23553?

Patch guidance is available from xen security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2026-23553.

CVE-2026-23553 - remediation guidance & executive summary

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.

CVSS Metrics

Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack Vector: local
Complexity: high
Privileges: none
User Action: none
Scope: unchanged
Confidentiality: low
Integrity: none
Availability: none
Weaknesses: CWE-665 CWE-693

Metadata

Primary Vendor: XEN
Published: 1/28/2026
Last Modified: 2/9/2026
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

CVE-2026-23553

Description

CVSS Metrics

Metadata

Affected Products

Remediation Guidance

Executive Summary