Is CVE-2026-42390 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-42390 being exploited in the wild.

How severe is CVE-2026-42390?

Medium severity, with a CVSS score of 5.3, published 25 June 2026.

Which products and versions are affected?

Powerdns Recursor 5.4.0 to 5.4.2.

Is there a fix for CVE-2026-42390?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-42390 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-42390?

Check whether you run Powerdns Recursor at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-42390: PowerDNS Recursor improper ZONEMD validation in ZoneToCache

CVE-2026-42390 · Severity: medium · CVSS 5.3 · Published 2026-06-25

PowerDNS Recursor, a tool used by internet service providers to look up website addresses for users, contains a flaw in how it validates certain DNS zone data. If configured to use ZONEMD validation, the software may incorrectly accept invalid or tampered DNS records. This could allow an attacker to provide incorrect network information to the system, potentially leading to users being directed to the wrong destinations.

Technologies: Powerdns Recursor. Vendors: Powerdns.

Quick answers

Is CVE-2026-42390 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-42390 being exploited in the wild.
How severe is CVE-2026-42390?: Medium severity, with a CVSS score of 5.3, published 25 June 2026.
Which products and versions are affected?: Powerdns Recursor 5.4.0 to 5.4.2.
Is there a fix for CVE-2026-42390?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-42390 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-42390?: Check whether you run Powerdns Recursor at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An improper input validation vulnerability (CWE-20) exists in PowerDNS Recursor's ZONEMD validation logic within the 'zonemd.cc' component. When the 'ZoneToCache' feature is configured with ZONEMD validation enabled, the recursor may fail to reject zones that do not meet the required cryptographic or structural integrity checks. A remote attacker could potentially exploit this to inject invalid zone data into the recursor's cache. The vulnerability affects version 5.4.0 and is fixed in version 5.4.3. Exploitation requires the specific 'ZoneToCache' configuration to be active.

Affected products

PowerDNS Recursor 5.4.0 to 5.4.2

Timeline

2026-06-25: disclosed
2026-06-25: advisory

References

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