CVE-2026-18508

Name	CVE-2026-18508
Description	A flaw was found in GNU tar. When extracting an archive with the --one-top-level option, hardlink targets are not confined to the designated top-level directory and may resolve relative to the extraction working directory. A crafted archive can create hardlinks that escape the intended boundary and, when combined with a preexisting symbolic link under the working directory, may allow writing outside that boundary during a single extraction.
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)
Debian Bugs	1143836

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
tar (PTS)	bullseye	1.34+dfsg-1+deb11u1	vulnerable
	bookworm	1.34+dfsg-1.2+deb12u1	vulnerable
	trixie	1.35+dfsg-3.1	vulnerable
	forky, sid	1.35+dfsg-5	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
tar	source	(unstable)	(unfixed)			1143836

[trixie] - tar <no-dsa> (Minor issue)
https://bugzilla.redhat.com/show_bug.cgi?id=2509843