Input validation error in PowerDNS Recursor - CVE-2026-42387

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Main Vulnerability Database Vulnerabilities #VU135386

Input validation error in PowerDNS Recursor - CVE-2026-42387

Published: June 25, 2026


Vulnerability identifier: #VU135386
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-2026-42387
CWE-ID: CWE-20
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 improper input validation in the ZoneToCache function when processing a crafted zone containing an invalid RRSIG record. A remote attacker can send a crafted zone to cause a denial of service.

Only configurations that use ZoneToCache are vulnerable.


Affected software

PowerDNS Recursor
Debian Linux
pdns-recursor (Debian package)

How to mitigate CVE-2026-42387

Install security update from vendor's website.

PowerDNS Recursor - addressed in versions 5.2.11, 5.3.8, 5.4.3
pdns-recursor (Debian package) - update to 5.2.11-0+deb13u1

External References

Related Security Bulletins