NULL pointer dereference in PowerDNS Recursor - CVE-2026-33601
Published: April 22, 2026
Vulnerability identifier: #VU126852
CSH Severity: Low
CVSS v4: 5.9 [CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-33601
CWE-ID: CWE-476
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to null pointer dereference in zoneToCache ZONEMD record handling when processing a crafted zonemd record from a malicious authoritative server. A remote privileged user can send a crafted zonemd record to cause a denial of service.
Exploitation requires the zoneToCache function to be configured.
Affected software
PowerDNS Recursor
Debian Linux
pdns-recursor (Debian package)
Debian Linux
pdns-recursor (Debian package)
How to mitigate CVE-2026-33601
Install security update from vendor's website.
PowerDNS Recursor - addressed in versions 5.2.9, 5.3.6, 5.4.1
pdns-recursor (Debian package) - update to 5.2.9-0+deb13u1
pdns-recursor (Debian package) - update to 5.2.9-0+deb13u1