CVE-2026-124742 Busybox: divide-by-zero in the volume_id fat prober via a zero sectors_per_cluster value
A crafted FAT filesystem can crash BusyBox volume probing utilities via divide-by-zero, disrupting device discovery and boot.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Harmful if only installed
- No
- Needs a specific call
- No
- Fix
- None listed
What is CVE-2026-124742?
CVE-2026-124742 is a medium-severity denial of service vulnerability in Red Hat Enterprise Linux 6, published on 11 Nov 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
A flaw was found in BusyBox. The volume identification component fails to properly validate cluster parameters when analyzing specially formatted FAT filesystems. An attacker able to present a crafted storage device or disk image can trigger a divide-by-zero condition when partition scanning utilities inspect the volume. This issue causes the probing utilities to crash unexpectedly, resulting in a Denial of Service (DoS) that can disrupt device discovery and system boot operations.
Weakness: CWE-369
Which versions are affected by CVE-2026-124742?
An affected version is exposed as installed. No special setting or call is needed.
How do I fix CVE-2026-124742?
No fix has been published for CVE-2026-124742 yet. Limit exposure of the affected software until one is available.
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-2026-124742 being exploited?
There is no known exploitation of CVE-2026-124742 in the wild and no public exploit code.
Sources
Also known as GHSA-whhw-82c4-82xv, UBUNTU-CVE-2026-124742.