CVE-2021-3752 Use after free in kernel

What is CVE-2021-3752?

CVE-2021-3752 is a high-severity use after free vulnerability in Debian Debian Linux, published on 16 Feb 2022. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A use-after-free flaw was found in the Linux kernel’s Bluetooth subsystem in the way user calls connect to the socket and disconnect simultaneously due to a race condition. This flaw allows a user to crash the system or escalate their privileges. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Weakness: CWE-362, CWE-416

Which versions are affected by CVE-2021-3752?

It affects 19 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Linux kernel, Netapp H300e Firmware, Netapp H300s Firmware, Netapp H410c Firmware and 13 more.

How do I fix CVE-2021-3752?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2021-3752 being exploited?

There is no known exploitation of CVE-2021-3752 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-2021-3752, GHSA-3f53-58pp-pg79, UBUNTU-CVE-2021-3752.