CVE-2021-3700: Debian Linux

Medium severity, CVSS 6.4. EPSS: 0.3% chance of exploitation in the next 30 days.

A use-after-free vulnerability was found in usbredir in versions prior to 0.11.0 in the usbredirparser_serialize() in usbredirparser/usbredirparser.c. This issue occurs when serializing large amounts of buffered write data in the case of a slow or blocked destination.

Affected products

• Debian Debian Linux: version 9.0 only
• Fedoraproject Fedora: version 34 only
• Red Hat Enterprise Linux: version 6.0 only; version 7.0 only; version 8.0 only
• Spice-Space Usbredir: before 0.11.0 (fixed in 0.11.0)

Published 2022-02-24. Last modified 2026-06-17.