[This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] To manage the system, sysctl and platform operations are used by the control domain or a possible Xenstore domain. Some of these operations may not be executed in parallel, so a system-wide lock each is used. The way those locks are acquired is, however, not providing any fairness. Furthermore, with XSM/Flask in use, the lock acquire will, for some operations, occur ahead of any permission checking. The sysctl issue is CVE-2026-62426. The platform-op issue is CVE-2026-62427.

Xenstore, to have an up-to-date picture of the entire system, wants to know of domains appearing and disappearing. To make this more robust, a new XEN_DOMCTL_get_domain_state was introduced. The management of the bitmap underlying that operation is tied into the binding of the VIRQ_DOM_EXC virtual IRQ. Unfortunately an error path there would tear down the bitmap even in cases when it wasn't set up. Unprivileged domains can trigger that error path.

Accesses to the CMOS memory contents are done using an indirect IO port pair. Therefore Xen needs to cache the guest chosen index, and one of the usages of the index didn't take the necessary locking to avoid concurrent changes. As a result, a guest could change the index after it being checked, causing a subsequent out-of-bound read access to the contents of an array.

The logic to handle periodic Viridian STIMERs performs a division with an unchecked user-controlled divisor value, that can be set to zero to cause a #DE fault.

[This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] With the introduction of Grant Table v2 came the requirement to be able to switch between versions. Switching from v1 to v2 reduces the number of valid grant references, as a bigger shared entry structure is then needed while the shared table doesn't change size. Switching from v2 back to v1 the status frames, which are separate in v2, go away. Code holding, but intermediately dropping and then re-acquiring the grant table lock, sometimes wrongly assumes that said properties wouldn't change across the window in time where the lock is not being held. The v1 -> v2 issue is CVE-2026-62435. The v2 -> v1 issue is CVE-2026-62436.