CVE-2026-42387Network attack vector

Resolver crash via invalid RRSIG processing

Published Jun 25, 2026 · Updated Jun 25, 2026

Denial of service in affected PowerDNS Recursor 5.2, 5.3, and 5.4 releases allows remote attackers to crash the resolver via a crafted zone. ZoneToCache processes an invalid RRSIG record from the supplied zone in zonemd.cc without sufficient validation, causing the Recursor process to terminate. Exploitation requires ZoneToCache and attacker control of a configured zone source; the reported consequence is a service crash without system compromise.

CVSS severity5.9
Medium
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in affected PowerDNS Recursor 5.2, 5.3, and 5.4 releases allows remote attackers to crash the resolver via a crafted zone. ZoneToCache processes an invalid RRSIG record from the supplied zone in zonemd.cc without sufficient validation, causing the Recursor process to terminate. Exploitation requires ZoneToCache and attacker control of a configured zone source; the reported consequence is a service crash without system compromise.

The record

CVE
CVE-2026-42387
Published
Jun 25, 2026
Updated
Jun 25, 2026
Vendor
PowerDNS
Product
PowerDNS Recursor
Classifications
CWE-20, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.2.0 <5.2.11
  2. Affected versionversion=5.3.0 <5.3.8
  3. Affected versionversion=5.4.0 <5.4.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PowerDNS · PowerDNS Recursorversion=5.2.0 <5.2.11; version=5.3.0 <5.3.8; version=5.4.0 <5.4.3

Published CVSS scores

5.9PowerDNSCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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