CVE-2026-23553
LOWDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 3% of all known CVEs.
References
Related Vulnerabilities
Other CWE-665 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-0847 | High | 7.8 | 90% | KEV | Fix |
| CVE-2022-22719 | High | 7.5 | 70% | - | Fix |
| CVE-2020-28019 | High | 7.5 | 62% | - | Fix |
| CVE-2022-46164 | Critical | 9.4 | 49% | - | Fix |
| CVE-2022-37128 | Critical | 9.8 | 21% | - | - |
| CVE-2019-14271 | Critical | 9.8 | 19% | - | Fix |
Common questions
How do I fix CVE-2026-23553?
Upgrade xen on debian 13 to 4.20.2+37-g61ff35323e-0+deb13u1 or later.
Is CVE-2026-23553 being actively exploited?
Not that we know of. CVE-2026-23553 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.13% is the estimated probability that it will be exploited in the next 30 days. That is higher than 3% of all scored CVEs.
How severe is CVE-2026-23553?
CVE-2026-23553 has a CVSS v3 base score of 2.9, rated low. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-23553 affect?
Published advisories record a fix for xen (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-23553
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-02-09.