CVE-2026-89593

Name	CVE-2026-89593
Description	In the Linux kernel, the following vulnerability has been resolved: hugetlb: only adjust reservation during unmapping if mapcount is 0 Since df7a6d1f6405, __unmap_hugepage_range can adjust reservations. In the case of folio mapped in both a parent and a child, if the parent unmaps the range first, the reservation adjustment will result in an underflow of the reserved count. Once the child unmaps the range, the count is restored. Change __unmap_hugepage_range() to check the mapcount before adjusting the reservation.
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)
References	DSA-6528-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
linux (PTS)	bookworm	6.1.176-1	fixed
	bookworm (security)	6.1.187-1	fixed
	trixie	6.12.107-1	vulnerable
	trixie (security)	6.12.111-1	fixed
	forky, sid	7.2.8-1	fixed

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

Package	Type	Release	Fixed Version	Origin
linux	source	bookworm	(not affected)
linux	source	trixie	6.12.111-1	DSA-6528-1
linux	source	(unstable)	7.2.6-1

[bookworm] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/5120b1e048d48596ffaec1a8412012a91adba73b (7.3-rc1)