CVE-2021-28706: Debian Linux

High severity, CVSS 8.6. EPSS: 2.2% chance of exploitation in the next 30 days.

guests may exceed their designated memory limit When a guest is permitted to have close to 16TiB of memory, it may be able to issue hypercalls to increase its memory allocation beyond the administrator established limit. This is a result of a calculation done with 32-bit precision, which may overflow. It would then only be the overflowed (and hence small) number which gets compared against the established upper bound.

Affected products

• Debian Debian Linux: version 11.0 only
• Fedoraproject Fedora: version 34 only; version 35 only
• Xen Xen: from 3.2, before 4.12 (fixed in 4.12)

Published 2021-11-24. Last modified 2026-06-17.