CVE-2026-23558: grant table v2 race in status page mapping

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-19 · updated 2026-10-14
Weakness: CWE-362

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.

Affected products

xen: from 4.0.0

References

https://xenbits.xenproject.org/xsa/advisory-486.html
http://www.openwall.com/lists/oss-security/2026/04/28/13
http://xenbits.xen.org/xsa/advisory-486.html

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