Xen Hypervisor OOB Read via CMOS Index Race
CVE-2026-62430 Published on July 28, 2026
x86: Out-of-bounds read in vRTC emulation
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.
Vulnerability Analysis
CVE-2026-62430 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity and availability.
Weakness Type
What is a Race Condition Vulnerability?
The program contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.
CVE-2026-62430 has been classified to as a Race Condition vulnerability or weakness.
Products Associated with CVE-2026-62430
Want to know whenever a new CVE is published for Citrix Xen Xen? stack.watch will email you.
