Use-after-free in NSD - CVE-2026-12245
Published: June 25, 2026
Vulnerability identifier: #VU135155
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-2026-12245
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 error logging on TLS connections when handling a DNS query over a DNS over TLS connection that is closed before the response is read. A remote attacker can send a DNS query over a DNS over TLS connection and close the connection early to cause a denial of service.
Only instances configured to use DNS over TLS are vulnerable.
Affected software
NSD
Fedora
Ubuntu
nsd (Ubuntu package)
nsd
Fedora
Ubuntu
nsd (Ubuntu package)
nsd
How to mitigate CVE-2026-12245
Install security update from vendor's website.
NSD - update to 4.14.3
nsd (Ubuntu package) - addressed in versions 4.1.7-1ubuntu0.1~esm1, 4.1.17-1ubuntu0.1~esm1, 4.1.26-1ubuntu0.1~esm1, 4.3.9-1ubuntu0.1~esm1, 4.8.0-1ubuntu0.1~esm1, 4.14.0-1ubuntu0.1~esm1
nsd - addressed in versions 4.14.3-1.fc43, 4.14.3-1.fc44, 4.15.0-1.el10_3
nsd (Ubuntu package) - addressed in versions 4.1.7-1ubuntu0.1~esm1, 4.1.17-1ubuntu0.1~esm1, 4.1.26-1ubuntu0.1~esm1, 4.3.9-1ubuntu0.1~esm1, 4.8.0-1ubuntu0.1~esm1, 4.14.0-1ubuntu0.1~esm1
nsd - addressed in versions 4.14.3-1.fc43, 4.14.3-1.fc44, 4.15.0-1.el10_3