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AuthoritativeApplication · Powerdns

CVE-2026-33610

HIGH · 7.5 CVSS v3.1 Published 2026-04-22
Fix available
A fix is available. Upgrade to 4.9.14 / 5.0.4 or later.
See remediation →
84/100
Remediation priority · High
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
A rogue primary server may cause file descriptor exhaustion and eventually a denial of service, when a PowerDNS secondary server forwards a DNS update request to it.

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

In PowerDNS, when a secondary server forwards DNS update requests to a primary server, a rogue or compromised primary server can cause the secondary to exhaust its available file descriptors by initiating numerous connections or failing to properly close them, ultimately resulting in denial of service.

MitigationImplement proper authentication (e.g., TSIG keys) for DNS zone transfers and updates, and restrict which servers are allowed to act as primary servers for each secondary. Additionally, implement connection limits and monitoring for abnormal file descriptor usage.

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:>= 4.9.0, < 4.9.14>= 5.0.0, < 5.0.4

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
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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. Check PowerDNS Authoritative version
    Run 'pdns --version' or check package manager (dpkg -l pdns-auth, rpm -qi pdns-auth)
    Affected if Version is >= 4.9.0 and < 4.9.14, OR >= 5.0.0 and < 5.0.4
  2. Verify server is configured as a secondary
    Check pdns.conf for 'secondary=yes' setting or review zone configuration files in /etc/pdns/zones/
    Affected if Server is configured as a secondary (secondary=yes in pdns.conf)
  3. Confirm DNS update forwarding is enabled
    Check pdnis.conf for 'allow-dnsupdate-from=' setting that permits primary server IP addresses
    Affected if allow-dnsupdate-from is configured to accept updates from primary servers
  4. Identify configured primary servers
    Review pdns.conf for 'primary-server=' directives or zone configuration for secondary zones
    Affected if Primary servers are defined for the secondary to forward updates to
  5. Monitor file descriptor usage
    Check current FD count: 'ls /proc/$(pidof pdns)/fd | wc -l' or 'lsof -p $(pidof pdns) | wc -l'
    Affected if File descriptor count is abnormally high or approaching ulimit -n value

A secondary server is affected if it runs a vulnerable PowerDNS version AND forwards DNS update requests to primary servers, making it susceptible to FD exhaustion from a malicious primary.

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 4.9.14 / 5.0.4 or later
Fixed in 4.9.145.0.4
Interim mitigation

Implement proper authentication (e.g., TSIG keys) for DNS zone transfers and updates, and restrict which servers are allowed to act as primary servers for each secondary. Additionally, implement connection limits and monitoring for abnormal file descriptor usage.

Recommended fix High confidence

4.9.14 or 5.0.4 (recommend latest 5.0.x stable release)

  1. 1. Identify the currently installed PowerDNS Authoritative Server version using your package manager or pdns_control version.
  2. 2. If running version 4.9.x (>= 4.9.0, < 4.9.14), upgrade to version 4.9.14.
  3. 3. If running version 5.0.x (>= 5.0.0, < 5.0.4), upgrade to version 5.0.4.
  4. 4. Use your package manager to perform the upgrade (e.g., apt-get update && apt-get install pdns-auth, yum update pdns-auth, or equivalent).
  5. 5. After upgrade, restart the PowerDNS Authoritative Server service to load the fixed version.
  6. 6. Verify the new version is running: pdns_control version.

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

Fix this in Authoritative Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

Scan for this in your stack

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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-2026-33610 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