CVE-2020-29571: Debian Linux

Medium severity, CVSS 6.2. EPSS: 0.4% chance of exploitation in the next 30 days.

An issue was discovered in Xen through 4.14.x. A bounds check common to most operation time functions specific to FIFO event channels depends on the CPU observing consistent state. While the producer side uses appropriately ordered writes, the consumer side isn't protected against re-ordered reads, and may hence end up de-referencing a NULL pointer. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. Only Arm systems may be vulnerable. Whether a system is vulnerable depends on the specific CPU. x86 systems are not vulnerable.

Affected products

• Debian Debian Linux: version 10.0 only
• Fedoraproject Fedora: version 32 only; version 33 only
• Xen Xen: from 4.4.0, up to and including 4.14.0

Published 2020-12-15. Last modified 2026-06-17.