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)

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 (security), trixie	6.12.107-1	vulnerable
	forky, sid	7.1.13-1	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
linux	source	bookworm	(not affected)
linux	source	(unstable)	(unfixed)

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