CVE-2021-47252 batman-adv: Avoid WARN_ON timing related checks

What is CVE-2021-47252?

CVE-2021-47252 is a medium-severity denial of service vulnerability in Linux kernel, published on 21 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

batman-adv: Avoid WARN_ON timing related checks

The soft/batadv interface for a queued OGM can be changed during the time the OGM was queued for transmission and when the OGM is actually transmitted by the worker.

But WARN_ON must be used to denote kernel bugs and not to print simple warnings. A warning can simply be printed using pr_warn.

Which versions are affected by CVE-2021-47252?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2021-47252?

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-2021-47252 being exploited?

There is no known exploitation of CVE-2021-47252 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2021-47252, GHSA-cwj6-5v55-7mj7, UBUNTU-CVE-2021-47252.