Use-after-free in ISC BIND - CVE-2026-5947
Published: May 22, 2026
Vulnerability identifier: #VU132115
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-2026-5947
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 SIG(0) validation when processing a DNS message signed with SIG(0) while the recursive-clients limit is reached during a query flood. A remote attacker can send specially crafted DNS traffic to cause a denial of service.
Both authoritative servers and resolvers are affected.
Affected software
ISC BIND
Debian Linux
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
Server Applications Module
Basesystem Module
Ubuntu
Fedora
LANTIME Operating System Firmware (LTOS)
bind9 (Ubuntu package)
bind9 (Debian package)
bind-utils-debuginfo
bind-utils
bind-debugsource
bind-debuginfo
bind
bind-doc
bind9-next
Debian Linux
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
Server Applications Module
Basesystem Module
Ubuntu
Fedora
LANTIME Operating System Firmware (LTOS)
bind9 (Ubuntu package)
bind9 (Debian package)
bind-utils-debuginfo
bind-utils
bind-debugsource
bind-debuginfo
bind
bind-doc
bind9-next
How to mitigate CVE-2026-5947
Install security update from vendor's website.
ISC BIND - addressed in versions 9.20.23, 9.20.23-S1, 9.21.22
LANTIME Operating System Firmware (LTOS) - update to 7.10.012
bind9 (Ubuntu package) - addressed in versions 1:9.18.39-0ubuntu0.22.04.4, 1:9.18.39-0ubuntu0.24.04.5, 1:9.20.11-1ubuntu2.4, 1:9.20.18-1ubuntu2.1
bind9 (Debian package) - addressed in versions 1:9.18.49-1~deb12u1, 1:9.20.23-1~deb13u1
bind-utils-debuginfo - update to 9.20.23-150700.3.25.1
bind-utils - update to 9.20.23-150700.3.25.1
bind-debugsource - update to 9.20.23-150700.3.25.1
bind-debuginfo - update to 9.20.23-150700.3.25.1
bind - update to 9.20.23-150700.3.25.1
bind-doc - update to 9.20.23-150700.3.25.1
bind9-next - addressed in versions 9.21.22-2.fc43, 9.21.22-2.fc44
LANTIME Operating System Firmware (LTOS) - update to 7.10.012
bind9 (Ubuntu package) - addressed in versions 1:9.18.39-0ubuntu0.22.04.4, 1:9.18.39-0ubuntu0.24.04.5, 1:9.20.11-1ubuntu2.4, 1:9.20.18-1ubuntu2.1
bind9 (Debian package) - addressed in versions 1:9.18.49-1~deb12u1, 1:9.20.23-1~deb13u1
bind-utils-debuginfo - update to 9.20.23-150700.3.25.1
bind-utils - update to 9.20.23-150700.3.25.1
bind-debugsource - update to 9.20.23-150700.3.25.1
bind-debuginfo - update to 9.20.23-150700.3.25.1
bind - update to 9.20.23-150700.3.25.1
bind-doc - update to 9.20.23-150700.3.25.1
bind9-next - addressed in versions 9.21.22-2.fc43, 9.21.22-2.fc44