CVE-2021-26931 Denial of service in n/a

What is CVE-2021-26931?

CVE-2021-26931 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 17 Feb 2021. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

An issue was discovered in the Linux kernel 2.6.39 through 5.10.16, as used in Xen. Block, net, and SCSI backends consider certain errors a plain bug, deliberately causing a kernel crash. For errors potentially being at least under the influence of guests (such as out of memory conditions), it isn't correct to assume a plain bug. Memory allocations potentially causing such crashes occur only when Linux is running in PV mode, though. This affects drivers/block/xen-blkback/blkback.c and drivers/xen/xen-scsiback.c.

Weakness: CWE-770

Which versions are affected by CVE-2021-26931?

It affects 3 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Linux kernel.

How do I fix CVE-2021-26931?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2021-26931 being exploited?

There is no known exploitation of CVE-2021-26931 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2021-26931, GHSA-rmvc-9pcc-7qpx, UBUNTU-CVE-2021-26931.