CVE-2026-62430
HighCVSS 7.5Summary
Accesses to CMOS memory contents are done using an indirect IO port pair. 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, allowing a guest to change the index after it being checked, causing an out-of-bound read access.
Risk Assessment
A malicious guest can read data out of bounds, potentially leading to information disclosure or system crash.
Recommendation
Apply the vendor patch for Xen that ensures proper locking when accessing the CMOS index.
Other vulnerabilities in Xen
See all- CVE-2026-62436Medium
When switching from Grant Table v2 to v1 in Xen, code holding the grant table lock but temporarily dropping and re-acquiring it wrongly assumes that table properties won't change during the window without the lock. This leads to issues with status frames that disappear when switching from v2 to v1.
- CVE-2026-62435Medium
When switching from Grant Table v1 to v2 in Xen, code holding the grant table lock but temporarily dropping and re-acquiring it wrongly assumes that table properties won't change during the window without the lock. This leads to a reduction in the number of valid grant references.
- CVE-2026-62434Medium
A guest with Populated on Demand (PoD) enabled may attempt to reclaim pages that are not regular guest RAM. This can cause corruption of memory management state in Xen.
- CVE-2026-62432High
The EVTCHNOP_expand_array hypercall checks for FIFO event channels being enabled, but without holding the correct lock. It can race with EVTCHNOP_reset, resulting in dereferencing a NULL pointer.
- CVE-2026-62431High
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.
- CVE-2026-62429Medium
Accessing vNUMA configuration data of a guest is still possible when domain destruction has already started. The cleanup of that configuration information is not synchronized with its retrieval by a device model controlling the guest.
- CVE-2026-62428High
When grant-copy operations are processed, permission checks may be carried out on a page different from the one involved in the copy when the grant is already pinned, leading to inconsistency.
- CVE-2026-62427High
Platform-op operations use a system-wide lock, but the lock acquisition lacks fairness, and with XSM/Flask enabled, the lock is acquired before permission checks. This is the platform-op issue.
- CVE-2026-62426High
Sysctl operations use a system-wide lock, but the lock acquisition lacks fairness, and with XSM/Flask enabled, the lock is acquired before permission checks. This is the sysctl issue.
- CVE-2026-42493High
Addressing certain issues related to long-running operations has proven overly costly. Since alternatives (HVM/PVH: HAP, PV: shim) are commonly available, the decision was to deprecate the functionality, while still retaining it for use at own risk. Memory-wise small guests may still be okay to run.
Original NVD description (English source)
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.