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CVE-2026-42387 PowerDNS CVE debrief

A vulnerability in the PowerDNS Recursor allows a malicious authoritative server to send a crafted zone that leads to a crash due to insufficient input validation. This issue has a CVSS score of 5.9 and is considered medium severity. The CVE record was published on 2026-06-25T14:16:39.447Z and was last modified on 2026-10-25T23:10:00.167Z. The vulnerability affects PowerDNS Recursor instances, and defenders should prioritize verifying and applying patches to prevent potential crashes. DNS administrators and security teams responsible for DNS infrastructure should assess exposure and verify input validation mechanisms.

Vendor
PowerDNS
Product
Recursor
CVSS
MEDIUM 5.9
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-25
Original CVE updated
2026-10-25
Advisory published
2026-06-25
Advisory updated
2026-10-25

Who should care

DNS administrators, security teams responsible for DNS infrastructure, and teams managing PowerDNS Recursor instances should assess exposure and verify input validation mechanisms to prevent potential crashes.

Why it matters

Defenders should prioritize verifying and applying patches for the PowerDNS Recursor to prevent potential crashes. DNS administrators and security teams responsible for DNS infrastructure should assess exposure and verify input validation mechanisms. The vulnerability has a CVSS score of 5.9 and is considered medium severity.

  • Potential crashes of PowerDNS Recursor instances
  • Need for verification and application of patches
  • Importance of validating input validation mechanisms
  • Potential impact on DNS service availability

Technical summary

The PowerDNS Recursor is vulnerable to a crash caused by insufficient input validation when receiving a crafted zone from a malicious authoritative server. This issue can be triggered via the ZoneToCache function. The vulnerability has a CVSS score of 5.9 and is considered medium severity. The issue requires verification and application of patches for PowerDNS Recursor, assessment of exposure, and validation of input validation mechanisms to prevent potential crashes.

Defensive priority

Defenders should prioritize verifying and applying patches for the PowerDNS Recursor to prevent potential crashes. DNS administrators and security teams responsible for DNS infrastructure should assess exposure and verify input validation mechanisms.

Recommended defensive actions

  • Verify and apply patches for PowerDNS Recursor
  • Assess exposure and validate input validation mechanisms
  • Monitor DNS infrastructure for potential crashes

Evidence notes

The CVE record and NVD entry provide details about the vulnerability, but the specific versions of PowerDNS Recursor affected are not clearly stated. The vendor, PowerDNS, has provided a security advisory (reference: https://docs.powerdns.com/recursor/security-advisories/powerdns-advisory-powerdns-2026-08.html).

Sources and references

Verified primary and authoritative sources

  • CVE-2026-42387 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-42387

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-42387 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-42387

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.