Is CVE-2026-23553 in the CISA KEV catalog?

No. CVE-2026-23553 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-23553?

CVE-2026-23553 has a CVSS v3 base score of 2.9 (LOW).

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

CVE-2026-23553 has an EPSS score of 0.13% (3th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-23553?

Upgrade xen on debian 13 to 4.20.2+37-g61ff35323e-0+deb13u1 or later.

CVE & CISA-KEV Catalog

CVE-2026-23553

LOW

2.9

CVSS v3

NVD

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.

CWE-665 CWE-693Protection Mechanism Failure

How to fix

Remediation Available

xenDebian

Fixed in:4.20.2+37-g61ff35323e-0+deb13u1CVE-2026-23553

Fixed in:4.20.2+37-g61ff35323e-1CVE-2026-23553

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

Attack VectorLocal

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Exploit Intelligence

0.13%probability of exploitation in 30 days

3rdpercentile

Low risk: more likely to be exploited than 3% of all known CVEs.

References

Patch3

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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.