Vulnerability in Xen
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.
Vulnerability class: Race Condition
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.001 (1.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 2nd percentile — 1.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: 0.000
Affected products
- Xen — versions consult Xen advisory XSA-486
Weakness classification (CWE)
References
- xenbits.xenproject.org/xsa/advisory-486.html (Patch, Mitigation, Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Patch, Mailing List, Third Party Advisory, Mitigation)
- af854a3a-2127-422b-91ae-364da2661108 (Patch, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-23558?
- CVE-2026-23558 is a high-severity vulnerability in Xen, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 7.8/10. Published 2026-05-19.
- How severe is CVE-2026-23558?
- High severity. CVSS v3 base score is 7.8 out of 10.