How severe is CVE-2026-23558?

CVE-2026-23558 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-23558 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-23558?

CVE-2026-23558 affects Xen. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-23558?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-23558 have an EU (EUVD) identifier?

Yes. CVE-2026-23558 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30928.

When was CVE-2026-23558 published?

CVE-2026-23558 was published on 2026-05-19 and last updated on 2026-06-17.

CVE-2026-23558

CVE-2026-23558 is a high-severity vulnerability in Xen with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-362.

Key facts

Severity: High (CVSS 3.x base score 7.8)
EPSS exploit prediction: 0% (2nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-30928
Weakness: CWE-362
Affected product: Xen
Published: 2026-05-19
Last modified: 2026-06-17

Description

The adjustments made for XSA-379 as well as those subsequently becoming XSA-387 still left a race window, when a HVM or PVH guest does a grant table version change from v2 to v1 in parallel with mapping the status page(s) via XENMEM_add_to_physmap. Some of the status pages may then be freed while mappings of them would still be inserted into the guest's secondary (P2M) page tables.

Frequently asked questions

What is CVE-2026-23558?: The adjustments made for XSA-379 as well as those subsequently becoming XSA-387 still left a race window, when a HVM or PVH guest does a grant table version change from v2 to v1 in parallel with mapping the status page(s) via XENMEM_add_to_physmap. Some of the status pages may then be freed while mappings of them would still be inserted into the guest's secondary (P2M) page tables.
How severe is CVE-2026-23558?: CVE-2026-23558 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-23558 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-23558?: CVE-2026-23558 affects Xen. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-23558?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-23558 have an EU (EUVD) identifier?: Yes. CVE-2026-23558 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30928.
When was CVE-2026-23558 published?: CVE-2026-23558 was published on 2026-05-19 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:*

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