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Vulnerability · Published Jul 22, 2026 · Assigned by isc

CVE-2026-12617Record ordering based unexpected exit with CNAME or DNAME

High 7.5

In plain English

A high-severity security flaw in BIND 9 from ISC. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.5%top 55.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

The issue is unexpected program termination based on ordering and/or specific content in responses to queries for CNAME or DNAME, and A records. Specifically, if a client queries for a DNAME and A record below the DNAME to the resolver, and the authoritative server responds positively to the A query but delays the DNAME response and later responds negatively, `named` may quit unexpectedly. Or, if a client queries for a CNAME and A record for the same name to the resolver, and the authoritative server responds positively to the A query but delays the CNAME response and later responds with a self-referential CNAME, the same failure may occur. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.22bind9.20.26-r0ALPINE-CVE-2026-12617
Alpine:v3.23bind9.20.26-r0ALPINE-CVE-2026-12617
Alpine:v3.24bind9.20.26-r0ALPINE-CVE-2026-12617
Debian:12bind91:9.18.49-1~deb12u2DEBIAN-CVE-2026-12617
Debian:13bind91:9.20.26-1~deb13u1DEBIAN-CVE-2026-12617
Debian:14bind91:9.20.26-1DEBIAN-CVE-2026-12617
Ubuntu:22.04:LTSbind91:9.18.39-0ubuntu0.22.04.5USN-8648-1
Ubuntu:22.04:LTSbind91:9.18.39-0ubuntu0.22.04.5UBUNTU-CVE-2026-12617
Ubuntu:24.04:LTSbind91:9.18.39-0ubuntu0.24.04.6UBUNTU-CVE-2026-12617
Ubuntu:24.04:LTSbind91:9.18.39-0ubuntu0.24.04.6USN-8648-1
Ubuntu:26.04:LTSbind91:9.20.24-1ubuntu0.2USN-8648-1
Ubuntu:26.04:LTSbind91:9.20.24-1ubuntu0.2UBUNTU-CVE-2026-12617
Ubuntu:22.04:LTSbind9-libsno fix listedUBUNTU-CVE-2026-12617
Ubuntu:24.04:LTSisc-dhcpno fix listedUBUNTU-CVE-2026-12617
Ubuntu:26.04:LTSisc-dhcpno fix listedUBUNTU-CVE-2026-12617

Affected products (as reported)

VendorProductVersions
ISC BIND 9 9.18.0 – through 9.18.509.20.0 – through 9.20.249.18.11-S1 – through 9.18.50-S19.20.9-S1 – through 9.20.24-S1

Weakness: CWE-617 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References