CVE-2021-26930: Debian Linux

High severity, CVSS 7.8. EPSS: 0.3% chance of exploitation in the next 30 days.

An issue was discovered in the Linux kernel 3.11 through 5.10.16, as used by Xen. To service requests to the PV backend, the driver maps grant references provided by the frontend. In this process, errors may be encountered. In one case, an error encountered earlier might be discarded by later processing, resulting in the caller assuming successful mapping, and hence subsequent operations trying to access space that wasn't mapped. In another case, internal state would be insufficiently updated, preventing safe recovery from the error. This affects drivers/block/xen-blkback/blkback.c.

Affected products

• Debian Debian Linux: version 9.0 only
• Fedoraproject Fedora: version 32 only; version 33 only
• Linux Linux Kernel: from 3.11, up to and including 5.10.16

Published 2021-02-17. Last modified 2026-06-17.