CVE-2026-81563

Name	CVE-2026-81563
Description	A BIND resolver encountering an SVCB/HTTPS AliasMode record referencing 14 or more SVCB/HTTPS ServiceMode records may fail to properly deallocate internal resources. If this happens repeatedly, resource exhaustion will eventually prevent the resolver from performing new recursive lookups. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.
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-6505-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
bind9 (PTS)	bookworm	1:9.18.49-1~deb12u1	vulnerable
	bookworm (security)	1:9.18.49-1~deb12u2	vulnerable
	trixie	1:9.20.26-1~deb13u1	vulnerable
	trixie (security)	1:9.20.29-1~deb13u1	fixed
	forky	1:9.20.27-2	vulnerable
	sid	1:9.20.29-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
bind9	source	trixie	1:9.20.29-1~deb13u1		DSA-6505-1
bind9	source	(unstable)	1:9.20.29-1

https://kb.isc.org/docs/cve-2026-81563