CVE-2026-5950

Name	CVE-2026-5950
Description	An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during bad-server handling, enabling a remote unauthenticated attacker to cause severe resource exhaustion by sending queries that trigger specific retry conditions. This issue affects BIND 9 versions 9.18.36 through 9.18.48, 9.20.8 through 9.20.22, 9.21.7 through 9.21.21, 9.18.36-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-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-6285-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
bind9 (PTS)	bullseye	1:9.16.50-1~deb11u2	vulnerable
	bullseye (security)	1:9.16.50-1~deb11u5	vulnerable
	bookworm	1:9.18.47-1~deb12u1	vulnerable
	bookworm (security)	1:9.18.49-1~deb12u1	fixed
	trixie	1:9.20.21-1~deb13u1	vulnerable
	trixie (security)	1:9.20.23-1~deb13u1	fixed
	forky	1:9.20.22-1	vulnerable
	sid	1:9.20.23-1	fixed

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

Package	Type	Release	Fixed Version	Origin
bind9	source	bookworm	1:9.18.49-1~deb12u1	DSA-6285-1
bind9	source	trixie	1:9.20.23-1~deb13u1	DSA-6285-1
bind9	source	(unstable)	1:9.20.23-1

https://kb.isc.org/docs/cve-2026-5950