CVE-2021-3669 Denial of service in kernel

What is CVE-2021-3669?

CVE-2021-3669 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 26 Aug 2022. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A flaw was found in the Linux kernel. Measuring usage of the shared memory does not scale with large shared memory segment counts which could lead to resource exhaustion and DoS.

Weakness: CWE-770, CWE-400

Which versions are affected by CVE-2021-3669?

It affects 23 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Ibm Spectrum Copy Data Management, Ibm Spectrum Protect Plus, Linux kernel, Redhat Build of Quarkus and 17 more.

How do I fix CVE-2021-3669?

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-2021-3669 being exploited?

There is no known exploitation of CVE-2021-3669 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 AZL-10676, AZL-34859, DEBIAN-CVE-2021-3669, GHSA-fr2g-fcjj-v8hc, UBUNTU-CVE-2021-3669.