Bug 2571620 (CVE-2026-124742)

Summary: CVE-2026-124742 busybox: Divide-by-zero in the volume_id FAT prober via a zero sectors_per_cluster value
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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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.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2571622, 2571623    
Bug Blocks:    

Description OSIDB Bzimport 2026-11-11 09:49:40 UTC
A flaw was found in BusyBox's volume_id FAT prober. A magic string in the boot sector, such as "FAT16   ", skips the geometry checks, so a sectors_per_cluster value of 0 can be used as a divisor, causing a divide-by-zero (SIGFPE) crash. A crafted filesystem image on an attached device triggers this when probed by blkid, findfs or mount LABEL=/UUID=, which probe every device in /proc/partitions; the crash prevents those applets from resolving any device and may fail boot or hotplug scripts that rely on them.