# CVE-2026-42396: PowerDNS Authoritative Server denial of service in catalog zone transfer

Source: https://junglewise.ai/threats/cve-2026-42396-powerdns-authoritative-server-denial-of-service-in-catalog-zone  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-21. Updated: 2026-05-21  
License: CC BY 4.0 with a link back

CVE-2026-42396 · Severity: medium · CVSS 4.9 · Published 2026-05-21

A vulnerability in PowerDNS Authoritative Server can cause failures in the synchronization of DNS zone data. This occurs when the system fails to properly validate specific member zone data during a catalog zone transfer. If exploited, this could lead to a denial of service for DNS management operations, preventing secondary servers from receiving updated records and potentially impacting the availability of domain name resolution.

Technologies: [Powerdns Authoritative Server](https://junglewise.ai/threats/technologies/authoritative-server). Vendors: [Powerdns](https://junglewise.ai/threats/vendors/powerdns).

## Quick answers

**Is CVE-2026-42396 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-42396 being exploited in the wild.

**How severe is CVE-2026-42396?** Medium severity, with a CVSS score of 4.9, published 21 May 2026.

**Which products and versions are affected?** PowerDNS Authoritative Server.

**Is there a fix for CVE-2026-42396?** 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-2026-42396 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-42396?** Check whether you run Powerdns Authoritative Server. 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

PowerDNS Authoritative Server is vulnerable to a denial of service condition during catalog zone transfers. The root cause is insufficient validation of member zone data within the catalog zone. An attacker with high privileges (sufficient to modify or inject data into a catalog zone) can provide malformed or unexpected member zone data that causes the transfer process to fail. This prevents the synchronization of DNS zones across the infrastructure. The vulnerability is tracked as CVE-2026-42396 and was reported by Open-Xchange.

## Affected products

- PowerDNS Authoritative Server

## Timeline

- 2026-05-21: disclosed: Initial advisory publication

## References

- [https://docs.powerdns.com/authoritative/security-advisories/powerdns-advisory-powerdns-2026-06.html](https://docs.powerdns.com/authoritative/security-advisories/powerdns-advisory-powerdns-2026-06.html)

## Related threats

- [PowerDNS Authoritative Server denial of service in internal web server](https://junglewise.ai/threats/cve-2026-42005-powerdns-authoritative-server-denial-of-service-in-internal-web)
- [PowerDNS Authoritative Server denial of service in GSS-TSIG](https://junglewise.ai/threats/cve-2026-42002-powerdns-authoritative-server-denial-of-service-in-gss-tsig)
- [PowerDNS Authoritative Server insufficient validation of Autoprimary SOA queries](https://junglewise.ai/threats/cve-2026-42001-powerdns-authoritative-server-insufficient-validation-of)
- [PowerDNS Authoritative Server insufficient name validation in AXFR](https://junglewise.ai/threats/cve-2026-42000-powerdns-authoritative-server-insufficient-name-validation-in)
- [PowerDNS Authoritative Server incorrect view handling with TCP PROXY](https://junglewise.ai/threats/cve-2026-41999-powerdns-authoritative-server-incorrect-view-handling-with-tcp)