Missing support for integrity check in PowerDNS Recursor - CVE-2026-33261

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Main Vulnerability Database Vulnerabilities #VU126850

Missing support for integrity check in PowerDNS Recursor - CVE-2026-33261

Published: April 22, 2026


Vulnerability identifier: #VU126850
CSH Severity: Medium
CVSS v4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-33261
CWE-ID: CWE-353
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 internal inconsistency in aggressive NSEC(3) cache when a zone transitions from NSEC to NSEC3. A remote attacker can trigger a zone transition from NSEC to NSEC3 to cause a denial of service.


Affected software

PowerDNS Recursor
Debian Linux
pdns-recursor (Debian package)

How to mitigate CVE-2026-33261

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

External References

Related Security Bulletins