Vulnerability · Published Jun 25, 2026 · Assigned by OX
CVE-2026-42387Insufficient input validation in ZoneToCache
Medium 5.9
In plain English
A medium-severity improper input validation in Recursor from PowerDNS. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)5.9Medium
Exploit odds (30 days)0.5%top 58.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.24 | pdns-recursor | 5.4.3-r0 | ALPINE-CVE-2026-42387 |
| Debian:12 | pdns-recursor | no fix listed | DEBIAN-CVE-2026-42387 |
| Debian:13 | pdns-recursor | 5.2.11-0+deb13u1 | DEBIAN-CVE-2026-42387 |
| Debian:14 | pdns-recursor | 5.4.3-1 | DEBIAN-CVE-2026-42387 |
| Ubuntu:24.04:LTS | pdns-recursor | no fix listed | UBUNTU-CVE-2026-42387 |
| Ubuntu:25.10 | pdns-recursor | no fix listed | UBUNTU-CVE-2026-42387 |
| Ubuntu:26.04:LTS | pdns-recursor | no fix listed | UBUNTU-CVE-2026-42387 |
| Ubuntu:26.10 | pdns-recursor | no fix listed | UBUNTU-CVE-2026-42387 |
Affected products (as reported)
Weakness: CWE-20 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H