Hypervisor data disclosure via unlocked vRTC index
Published Jul 28, 2026 · Updated Jul 28, 2026
Out-of-bounds read in Xen 3.2 and later allows guest OS users to disclose Xen data through concurrent vRTC index changes. The vRTC CMOS I/O path caches a guest-selected index, then validates and reads the backing array without holding the lock that prevents the guest from changing that index. Only HVM guests expose the vulnerable emulation; PV- and PVH-only hosts avoid it, and the disclosed memory excludes data belonging to other guests.
Summary
What happened
Out-of-bounds read in Xen 3.2 and later allows guest OS users to disclose Xen data through concurrent vRTC index changes. The vRTC CMOS I/O path caches a guest-selected index, then validates and reads the backing array without holding the lock that prevents the guest from changing that index. Only HVM guests expose the vulnerable emulation; PV- and PVH-only hosts avoid it, and the disclosed memory excludes data belonging to other guests.
The record
- CVE
- CVE-2026-62430
- Published
- Jul 28, 2026
- Updated
- Jul 28, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-362, T1005
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 28, 2026CVE publishedPublication date reported by the CVE source.
- Jul 28, 2026Record updatedLatest update available in the CVE record.
Exploitability
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Published CVSS scores
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Attacks
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