CVE-2021-3612 Memory corruption in kernel

What is CVE-2021-3612?

CVE-2021-3612 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 9 Jul 2021. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

An out-of-bounds memory write flaw was found in the Linux kernel's joystick devices subsystem in versions before 5.9-rc1, in the way the user calls ioctl JSIOCSBTNMAP. This flaw allows a local user to crash the system or possibly escalate their privileges on the system. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Weakness: CWE-787, CWE-20

Which versions are affected by CVE-2021-3612?

It affects 17 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Linux kernel, Netapp Cloud Backup, Netapp H300e Firmware, Netapp H300s Firmware and 11 more.

How do I fix CVE-2021-3612?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2021-3612 being exploited?

There is no known exploitation of CVE-2021-3612 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 DEBIAN-CVE-2021-3612, GHSA-3g5m-332q-27r3, UBUNTU-CVE-2021-3612.