CVE-2026-42000Network attack vector

BIND backend outage via unescaped AXFR names

Published May 21, 2026 · Updated May 21, 2026

Name validation in PowerDNS Authoritative Server 4.9.0 through 4.9.14 and 5.0.0 through 5.0.4 allows remote attackers to disable the BIND backend. During AXFR, bindbackend2.cc writes DNS names containing special characters such as $ or @ into BIND configuration without escaping them, producing an unparseable file. Exploitation requires a crafted zone transfer to a server using the BIND backend; that backend remains unavailable until the configuration is manually repaired.

CVSS severity6.8
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Name validation in PowerDNS Authoritative Server 4.9.0 through 4.9.14 and 5.0.0 through 5.0.4 allows remote attackers to disable the BIND backend. During AXFR, bindbackend2.cc writes DNS names containing special characters such as $ or @ into BIND configuration without escaping them, producing an unparseable file. Exploitation requires a crafted zone transfer to a server using the BIND backend; that backend remains unavailable until the configuration is manually repaired.

The record

CVE
CVE-2026-42000
Published
May 21, 2026
Updated
May 21, 2026
Vendor
PowerDNS
Product
PowerDNS Authoritative Server
Classifications
CWE-77, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 2026CVE publishedPublication date reported by the CVE source.
  2. May 21, 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=4.9.0 <4.9.15
  2. Affected versionversion=5.0.0 <5.0.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PowerDNS · PowerDNS Authoritative Serverversion=4.9.0 <4.9.15; version=5.0.0 <5.0.5

Published CVSS scores

8.6NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
6.8Open-XchangeCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/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.

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-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
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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