CVE-2026-6791

Name	CVE-2026-6791
Description	When expanding paths that begin with a tilde (~) followed by a username, the internal parse_tilde function extracts the username to determine the user's home directory. The implementation allocates memory for this username directly on the stack using the strndupa macro. Because the size of this allocation was determined by the length of the user-supplied input without any bounds checks, passing an excessively long username e.g. thousands of characters, forces the thread to exhaust its stack space. Thus if an application passes untrusted, attacker-controlled input to the wordexp function, an attacker can trigger a stack clash.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
glibc (PTS)	bullseye	2.31-13+deb11u11	vulnerable
	bullseye (security)	2.31-13+deb11u14	vulnerable
	bookworm	2.36-9+deb12u14	vulnerable
	bookworm (security)	2.36-9+deb12u7	vulnerable
	trixie	2.41-12+deb13u3	vulnerable
	forky	2.43-3	fixed
	sid	2.43-4	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
glibc	source	(unstable)	2.43-3

Notes

[trixie] - glibc <no-dsa> (Minor issue)
https://sourceware.org/bugzilla/show_bug.cgi?id=34091
https://sourceware.org/git/?p=glibc.git;a=blob;f=advisories/GLIBC-SA-2026-0013