CVE-2021-34556: Debian Linux

Medium severity, CVSS 5.5. EPSS: 0.4% chance of exploitation in the next 30 days.

In the Linux kernel through 5.13.7, an unprivileged BPF program can obtain sensitive information from kernel memory via a Speculative Store Bypass side-channel attack because the protection mechanism neglects the possibility of uninitialized memory locations on the BPF stack.

Affected products

• Debian Debian Linux: version 9.0 only
• Fedoraproject Fedora: version 33 only; version 34 only
• Linux Linux Kernel: up to and including 5.13.7

Published 2021-08-02. Last modified 2026-10-08.