CVE-2026-42389Network attack vector

Cache poisoning via invalid authoritative reply headers

Published Jun 25, 2026 · Updated Jun 25, 2026

Improper input validation in PowerDNS Recursor 5.4.0 through 5.4.2 allows remote attackers to poison the DNS cache via spoofed replies. The incoming-response path fails to reject authoritative DNS replies carrying invalid header values before their data reaches cache processing. Exploitation requires crafted authoritative replies combined with massive spoofing; the vendor reports no resulting system compromise.

CVSS severity5.3
Medium
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in PowerDNS Recursor 5.4.0 through 5.4.2 allows remote attackers to poison the DNS cache via spoofed replies. The incoming-response path fails to reject authoritative DNS replies carrying invalid header values before their data reaches cache processing. Exploitation requires crafted authoritative replies combined with massive spoofing; the vendor reports no resulting system compromise.

The record

CVE
CVE-2026-42389
Published
Jun 25, 2026
Updated
Jun 25, 2026
Vendor
PowerDNS
Product
PowerDNS Recursor
Classifications
CWE-20, T1565.002
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=5.4.0 <5.4.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PowerDNS · PowerDNS Recursorversion=5.4.0 <5.4.3

Published CVSS scores

5.3PowerDNSCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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
T1565.002Transmitted Data Manipulation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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