dbcve.org
AuthoritativeApplication · Powerdns

CVE-2026-42000

HIGH · 8.6 CVSS v3.1 Published 2026-05-21
Fix available
A fix is available. Upgrade to 4.9.15 / 5.0.5 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Insufficient Validation of Names During AXFR

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

This is a DNS vulnerability involving insufficient validation of names during AXFR (Authoritative Zone Transfer) operations. AXFR is used to transfer entire DNS zone files between servers. The lack of proper name validation could allow attackers to request or manipulate zone transfers in unauthorized ways, potentially exposing DNS zone data or enabling further attacks.

MitigationImplement strict access controls on AXFR (allow-listing authorized secondary DNS servers by IP) and add proper validation of names/records being transferred to prevent unauthorized zone data exposure or manipulation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
AuthoritativeApplication
Affected:< 4.9.15>= 5.0.0, < 5.0.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Powerdns Authoritative version
    Run 'pdns_server --version' or 'pdns_control version' to retrieve the installed Powerdns Authoritative version number
    Affected if The version is less than 4.9.15, OR greater than or equal to 5.0.0 but less than 5.0.5
  2. Confirm AXFR is enabled
    Inspect the Powerdns configuration file (typically pdns.conf) for directives that enable AXFR transfers, such as 'allow-axfr-ips', 'disable-axfr', or 'master'/'slave' server roles
    Affected if AXFR is enabled (allow-axfr-ips is set to any value, or disable-axfr is not set to 'yes') and the server is configured as a master or secondary
  3. Verify AXFR is accessible to untrusted sources
    Review the 'allow-axfr-ips' setting in pdns.conf - check if it permits IPs outside your trusted secondary DNS server list, or if it is set to '0.0.0.0/0'
    Affected if The server allows AXFR requests from untrusted or any IP addresses (allow-axfr-ips includes 0.0.0.0/0, is not set, or allows IPs beyond your known secondary servers)
  4. Confirm zone transfer configuration
    Check if the server is configured as a primary/master (primary=yes in pdns.conf) or as a secondary/slave (secondary=yes), as AXFR requires one of these roles to serve or receive zone transfers
    Affected if The server has primary=yes or secondary=yes configured in pdns.conf

You are affected if your Powerdns Authoritative version falls within the vulnerable ranges (below 4.9.15 or between 5.0.0 and 5.0.5) AND AXFR transfers are enabled with access from untrusted sources.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.9.15 / 5.0.5 or later
Fixed in 4.9.155.0.5
Interim mitigation

Implement strict access controls on AXFR (allow-listing authorized secondary DNS servers by IP) and add proper validation of names/records being transferred to prevent unauthorized zone data exposure or manipulation.

Recommended fix High confidence

PowerDNS Authoritative Server 4.9.15 (4.x branch) or 5.0.5 (5.x branch)

  1. Identify the currently running PowerDNS Authoritative Server version using 'pdns_version' or checking package version
  2. If running version < 4.9.15 (4.x branch): upgrade to version 4.9.15 or later
  3. If running version >= 5.0.0 and < 5.0.5 (5.x branch): upgrade to version 5.0.5 or later
  4. For Linux systems using package managers: update via apt-get update && apt-get install pdns-auth or yum update pdns-auth as appropriate
  5. After upgrade, restart the PowerDNS service (systemctl restart pdns)
  6. Verify AXFR transfers work correctly and the server is responding properly
Caveat Security-focused upgrade; minimal expected breaking changes, but review release notes for any configuration or behavior changes between versions

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Authoritative Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing5.0 h
  • Review / QA3.0 h
17.0 hours of engineering $2,970
Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-42000 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data