# CVE-2026-42388: PowerDNS Recursor denial of service in Catalog Zones

Source: https://junglewise.ai/threats/cve-2026-42388-powerdns-recursor-denial-of-service-in-catalog-zones  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-25. Updated: 2026-06-25  
License: CC BY 4.0 with a link back

CVE-2026-42388 · Severity: medium · CVSS 5.9 · Published 2026-06-25

A vulnerability in PowerDNS Recursor's Catalog Zones feature can cause the DNS service to crash. PowerDNS Recursor is a widely used tool that translates human-readable domain names into IP addresses for internet users. If exploited, this flaw could lead to a denial-of-service, preventing users from accessing websites and other online services.

Technologies: [Powerdns Recursor](https://junglewise.ai/threats/technologies/recursor). Vendors: [Powerdns](https://junglewise.ai/threats/vendors/powerdns).

## Quick answers

**Is CVE-2026-42388 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-42388 being exploited in the wild.

**How severe is CVE-2026-42388?** Medium severity, with a CVSS score of 5.9, published 25 June 2026.

**Which products and versions are affected?** Powerdns Recursor 5.2.0 to 5.2.10, 5.3.0 to 5.3.7, 5.4.0 to 5.4.2.

**Is there a fix for CVE-2026-42388?** 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-2026-42388 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-42388?** 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

A denial-of-service vulnerability exists in PowerDNS Recursor due to incomplete validation of Start of Authority (SOA) records within Catalog Zones. The flaw is located in the rec-xfr.cc component. A remote attacker could potentially trigger a service crash by providing a specially crafted SOA record in a catalog zone. The attack requires a high degree of complexity (AC:H), likely involving the ability to influence or provide catalog zone data. Affected versions include the 5.2, 5.3, and 5.4 branches; users should update to versions 5.2.11, 5.3.8, or 5.4.3 respectively.

## Affected products

- PowerDNS Recursor 5.2.0 to 5.2.10, 5.3.0 to 5.3.7, 5.4.0 to 5.4.2

## Timeline

- 2026-06-25: disclosed: CVE published by Open-Xchange
- 2026-06-25: advisory: PowerDNS security advisory 2026-08 released

## References

- [https://repo.powerdns.com/](https://repo.powerdns.com/)
- [https://docs.powerdns.com/recursor/security-advisories/powerdns-advisory-powerdns-2026-08.html](https://docs.powerdns.com/recursor/security-advisories/powerdns-advisory-powerdns-2026-08.html)

## Related threats

- [PowerDNS Recursor DNSSEC wildcard validation bypass in RRSIG processing](https://junglewise.ai/threats/cve-2026-52688-powerdns-recursor-dnssec-wildcard-validation-bypass-in-rrsig)
- [PowerDNS Recursor DNSSEC validation bypass in wildcard CNAME/DNAME records](https://junglewise.ai/threats/cve-2026-52686-powerdns-recursor-dnssec-validation-bypass-in-wildcard-cname)
- [PowerDNS Recursor TTL capping bypass in NS record refresh](https://junglewise.ai/threats/cve-2026-52684-powerdns-recursor-ttl-capping-bypass-in-ns-record-refresh)
- [PowerDNS Recursor DNSSEC validation failure via EDNS spoofing](https://junglewise.ai/threats/cve-2026-52690-powerdns-recursor-dnssec-validation-failure-via-edns-spoofing)
- [PowerDNS Recursor improper ZONEMD validation in ZoneToCache](https://junglewise.ai/threats/cve-2026-42390-powerdns-recursor-improper-zonemd-validation-in-zonetocache)