CVE-2021-4028 Use after free in kernel

High 7.8 Published 24 Aug 2022 Updated 3 Aug 2024

A local attacker can exploit a use-after-free in the Linux kernel RDMA listener to crash the system or escalate privileges.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2021-4028?

CVE-2021-4028 is a high-severity use after free vulnerability in Linux kernel, published on 24 Aug 2022. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A flaw in the Linux kernel's implementation of RDMA communications manager listener code allowed an attacker with local access to setup a socket to listen on a high port allowing for a list element to be used after free. Given the ability to execute code, a local attacker could leverage this use-after-free to crash the system or possibly escalate privileges on the system.

Weakness: CWE-416

Which versions are affected by CVE-2021-4028?

It affects 2 products.

Linux distribution packages (17)

`kernel` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`kernel-abi-whitelists` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`kernel-debug` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`kernel-debug-debuginfo` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`kernel-debug-devel` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`kernel-debuginfo` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`kernel-debuginfo-common-x86_64` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`kernel-devel` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`kernel-doc` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`kernel-tools` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`kernel-tools-debuginfo` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`kernel-tools-libs` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`kernel-tools-libs-devel` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`perf` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`perf-debuginfo` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`python-perf` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`
`python-perf-debuginfo` Red Hat:rhel_aus:7.4::server	All versions	`0:3.10.0-693.100.1.el7`

Products include Linux kernel, Suse Linux Enterprise.

How do I fix CVE-2021-4028?

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-2021-4028 being exploited?

There is no known exploitation of CVE-2021-4028 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as DEBIAN-CVE-2021-4028, GHSA-qfcc-9m6r-r23m, RHSA-2022:2188, UBUNTU-CVE-2021-4028.