CVE-2021-28688 Memory corruption in Linux

Medium 6.5 Published 6 Apr 2021 Updated 3 Aug 2024

A regression in the Linux kernel's Xen grant table cleanup logic causes resource leaks and zombie domains, leading to denial of service and potential information disclosure.

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-2021-28688?

CVE-2021-28688 is a medium-severity memory corruption vulnerability in Debian Debian Linux, published on 6 Apr 2021. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

The fix for XSA-365 includes initialization of pointers such that subsequent cleanup code wouldn't use uninitialized or stale values. This initialization went too far and may under certain conditions also overwrite pointers which are in need of cleaning up. The lack of cleanup would result in leaking persistent grants. The leak in turn would prevent fully cleaning up after a respective guest has died, leaving around zombie domains. All Linux versions having the fix for XSA-365 applied are vulnerable. XSA-365 was classified to affect versions back to at least 3.11.

Weakness: CWE-665

Which versions are affected by CVE-2021-28688?

It affects 2 products.

Linux distribution packages (4)

`kgraft-patch-SLE12-SP3_Update_38` SUSE:Linux Enterprise Server 12 SP3-LTSS	All versions	`3-2.2`
`kgraft-patch-SLE12-SP3_Update_43` SUSE:Linux Enterprise Server 12 SP3-LTSS	All versions	`2-2.1`
`kgraft-patch-SLE12-SP3_Update_38` SUSE:Linux Enterprise Server for SAP Applications 12 SP3	All versions	`3-2.2`
`kgraft-patch-SLE12-SP3_Update_43` SUSE:Linux Enterprise Server for SAP Applications 12 SP3	All versions	`2-2.1`

Products include Debian Debian Linux, Linux kernel.

How do I fix CVE-2021-28688?

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-2021-28688 being exploited?

There is no known exploitation of CVE-2021-28688 in the wild and no public exploit code.

All Debian Debian Linux vulnerabilities

Sources

Also known as DEBIAN-CVE-2021-28688, GHSA-hqhv-rx9w-cr56, SUSE-SU-2021:1341-1, SUSE-SU-2022:1003-1, UBUNTU-CVE-2021-28688.