What is CVE-2026-42387?

CVE-2026-42387 is a medium-severity vulnerability in Powerdns Recursor, classified under Improper Input Validation. CVSS score: 5.9/10. Published 2026-06-25.

How severe is CVE-2026-42387?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Improper input validation in Powerdns Recursor

CVE-2026-42387

A malicious authoritative server can send a crafted zone via the ZoneToCache function that leads to a crash of the Recursor due to insuffcient input validation.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Powerdns Recursor — versions 5.2.0, 5.3.0, 5.4.0

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

security@open-xchange.com

Frequently asked questions

What is CVE-2026-42387?: CVE-2026-42387 is a medium-severity vulnerability in Powerdns Recursor, classified under Improper Input Validation. CVSS score: 5.9/10. Published 2026-06-25.
How severe is CVE-2026-42387?: Medium severity. CVSS v3 base score is 5.9 out of 10.