| Name | CVE-2026-11721 |
| Description | It is possible for an attacker's zone to respond to a query with an RRSIG that has a smaller number of labels than the zone in which the RRSIG is contained. This causes `named` to produce a wildcard name for a zone that is shorter than the attacker's zone, which can result in cache poisoning. For this attack to have any effect, the resolver under attack must have set `synth-from-dnssec yes;` (which is the default). This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-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 | DLA-4725-1, DSA-6395-1 |
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~deb11u6 | fixed | |
| bookworm | 1:9.18.49-1~deb12u1 | vulnerable | |
| bookworm (security) | 1:9.18.49-1~deb12u2 | fixed | |
| trixie | 1:9.20.23-1~deb13u1 | vulnerable | |
| trixie (security) | 1:9.20.26-1~deb13u1 | fixed | |
| forky, sid | 1:9.20.26-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| bind9 | source | bullseye | 1:9.16.50-1~deb11u6 | DLA-4725-1 | ||
| bind9 | source | bookworm | 1:9.18.49-1~deb12u2 | DLA-4725-1 | ||
| bind9 | source | trixie | 1:9.20.26-1~deb13u1 | DSA-6395-1 | ||
| bind9 | source | (unstable) | 1:9.20.26-1 |
https://kb.isc.org/docs/cve-2026-11721
https://gitlab.isc.org/isc-projects/bind9/-/commit/5f1d1f35d8ea137ee3afefbe50d76a9fb1199ab7 (9.16-branch)
https://gitlab.isc.org/isc-projects/bind9/-/commit/71dadba745c5d2ca7e1d4788fccab3a7d6a929f2 (9.16-branch)
https://gitlab.isc.org/isc-projects/bind9/-/commit/ebf391bdb8ea196dab43d0a1e1f639458cb15126 (9.16-branch)
https://gitlab.isc.org/isc-projects/bind9/-/commit/1a4986e2533f87e80eb21da3f06708d335aff1e2 (9.18-branch)
https://gitlab.isc.org/isc-projects/bind9/-/commit/15089066b15f826d7487c3d160b5872820f84b83 (9.18-branch)
https://gitlab.isc.org/isc-projects/bind9/-/commit/19e496ca260b6a756ae1378e8ebcbdb666b7d9ed (9.18-branch)