Input validation error in PowerDNS Recursor - CVE-2026-42389
Published: June 25, 2026
Vulnerability identifier: #VU135395
CSH Severity: Low
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-42389
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to poison the cache.
The vulnerability exists due to improper input validation in incoming answers from authoritative servers when processing crafted replies with invalid header values. A remote attacker can send spoofed crafted replies to poison the cache.
Exploitation requires massive spoofing attempts.
Affected software
PowerDNS Recursor
How to mitigate CVE-2026-42389
Install security update from vendor's website.
PowerDNS Recursor - update to 5.4.3