Bug 2531353 (CVE-2026-88839)

Summary:	CVE-2026-88839 busybox: busybox: passwd/group parser writes heap pointers out of bounds due to stale tokenize() endpoint
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	security-response-team
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
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Fixed In Version:		Doc Type:	---
Doc Text:	BusyBox passwd/group tokenize() references a stale endpoint pointer after trimming, causing an out-of-bounds write of heap pointers.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-10 09:48:23 UTC

A vulnerability exists in the BusyBox passwd and group file parser in libpwdgrp/pwd_grp.c. The tokenize() function trims trailing whitespace via overlapping_strcpy() but continues to reference the stale *end pointer, causing tokenize_end to be too large. This under-allocates in parse_common(), and convert_to_struct() then writes gr_mem[] pointers past the end of the heap allocation.

Triggering the vulnerability requires injecting malformed entries with whitespace before commas into /etc/group, then invoking any applet that calls getgrnam().