Use-after-free in ISC BIND - CVE-2026-19666
Published: September 16, 2026
Vulnerability identifier: #VU150225
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-19666
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to use-after-free in query_addnoqnameproof() via the DNS64 filter64 path when processing a malformed applicable answer from an authoritative server. A remote attacker can send a malformed applicable DNS answer to cause a denial of service.
Only resolvers configured to use dns64 are affected.
Affected software
ISC BIND
Debian Linux
bind9 (Debian package)
Debian Linux
bind9 (Debian package)
How to mitigate CVE-2026-19666
Install security update from vendor's website.
ISC BIND - addressed in versions 9.20.29, 9.20.29-s1, 9.21.26
bind9 (Debian package) - update to 1:9.20.29-1~deb13u1
bind9 (Debian package) - update to 1:9.20.29-1~deb13u1