CVE-2021-3679

MEDIUM

Linux Kernel < 5.14 - Authenticated Denial of Service via Trace Ring Buffer Resource Starvation

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2021-3679. PoCs published by aegistudio.

AI-analyzed exploit summary This repository contains a functional proof-of-concept exploit for CVE-2021-3679, which triggers a logic bug in `rb_per_cpu_empty` leading to a kernel-space deadloop. The exploit demonstrates a denial-of-service (DoS) condition by spawning a `dd` process that consumes a CPU core and cannot be terminated by standard UNIX signals.

Description

A lack of CPU resource in the Linux kernel tracing module functionality in versions prior to 5.14-rc3 was found in the way user uses trace ring buffer in a specific way. Only privileged local users (with CAP_SYS_ADMIN capability) could use this flaw to starve the resources causing denial of service.

Exploits (1)

nomisec WORKING POC 9 stars
by aegistudio · poc
https://github.com/aegistudio/RingBufferDetonator

This repository contains a functional proof-of-concept exploit for CVE-2021-3679, which triggers a logic bug in `rb_per_cpu_empty` leading to a kernel-space deadloop. The exploit demonstrates a denial-of-service (DoS) condition by spawning a `dd` process that consumes a CPU core and cannot be terminated by standard UNIX signals.

Classification
Working Poc 95%
Attack Type
Dos
Complexity
Moderate
Reliability
Reliable
Target: Linux kernel versions 3.10 to 5.14-rc1
Auth required
Prerequisites: root privileges · gcc · realpath · nm · awk · grep
devstral-2 · analyzed Feb 18, 2026 Full analysis →

References (5)

Core 5
Core References
Issue Tracking, Patch, Third Party Advisory x_refsource_misc
https://bugzilla.redhat.com/show_bug.cgi?id=1989165
Third Party Advisory vendor-advisory x_refsource_debian
https://www.debian.org/security/2021/dsa-4978
Mailing List, Third Party Advisory mailing-list x_refsource_mlist
https://lists.debian.org/debian-lts-announce/2021/10/msg00010.html
Mailing List, Third Party Advisory mailing-list x_refsource_mlist
https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html

Scores

CVSS v3 5.5
EPSS 0.0074
EPSS Percentile 49.7%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Details

CWE
CWE-400 CWE-835
Status published
Products (5)
debian/debian_linux 9.0
debian/debian_linux 10.0
linux/linux_kernel 5.14 (3 CPE variants)
linux/linux_kernel < 5.14
redhat/enterprise_linux 8.0
Published Aug 05, 2021
Tracked Since Feb 18, 2026