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DnsdistApplication · Powerdns

CVE-2026-33599

HIGH · 8.1 CVSS v3.1 Published 2026-04-22
Fix available
A fix is available. Upgrade to 1.9.13 / 2.0.4 or later.
See remediation →
86/100
Remediation priority · High
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 backend can send a crafted SVCB response to a Discovery of Designated Resolvers request, when requested via either the autoUpgrade (Lua) option to newServer or auto_upgrade (YAML) settings. DDR upgrade is not enabled by default.

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 Recursor, when the autoUpgrade (Lua) or auto_upgrade (YAML) setting is enabled for DDR (Discovery of Designated Resolvers), a rogue or compromised backend DNS server can send a specially crafted SVCB response that could be mishandled, potentially leading to improper resolution behavior or security implications.

MitigationDo not enable the autoUpgrade/auto_upgrade feature for DDR unless all backend servers are fully trusted and secured. Monitor for unexpected SVCB responses and ensure backend servers implement proper validation.

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
DnsdistApplication
Affected:>= 1.9.0, < 1.9.13>= 2.0.0, < 2.0.4

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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/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 Dnsdist version
    Run 'dnsdist --version' or check the installed package version using your system's package manager (e.g., 'dpkg -l dnsdist' or 'rpm -qi dnsdist')
    Affected if The installed version falls within >= 1.9.0 and < 1.9.13, or >= 2.0.0 and < 2.0.4
  2. Locate the dnsdist configuration file
    Check common locations such as /etc/dnsdist.conf, /etc/dnsdist/dnsdist.conf, or the path specified via the -C command-line flag
    Affected if A configuration file exists and is in use
  3. Verify if auto_upgrade (YAML) is enabled for DDR
    Search the configuration file for 'autoUpgrade' or 'auto_upgrade' settings related to DDR or SVCB records. Look for lines like 'setDDRAutoUpgrade(true)' or similar DDR auto-upgrade configurations
    Affected if The autoUpgrade or auto_upgrade setting for DDR is explicitly enabled (set to true or similar)
  4. Check for Lua-based autoUpgrade configuration
    If using a Lua configuration file (typically with .lua extension), search for 'autoUpgrade' or 'autoUpgradeDDR' function calls related to DDR/SVCB handling
    Affected if A Lua script loads and enables the autoUpgrade function for DDR handling

The environment is affected if dnsdist version is within the vulnerable ranges AND the autoUpgrade/auto_upgrade feature for DDR is explicitly enabled in the configuration.

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 1.9.13 / 2.0.4 or later
Fixed in 1.9.132.0.4
Interim mitigation

Do not enable the autoUpgrade/auto_upgrade feature for DDR unless all backend servers are fully trusted and secured. Monitor for unexpected SVCB responses and ensure backend servers implement proper validation.

Recommended fix High confidence

Upgrade to dnsdist 1.9.13 or later for the 1.9.x branch, or 2.0.4 or later for the 2.0.x branch

  1. 1. Identify the current dnsdist version using 'dnsdist --version'
  2. 2. If running version 1.9.x (>=1.9.0 and <1.9.13), plan upgrade to 1.9.13 or later
  3. 3. If running version 2.0.x (>=2.0.0 and <2.0.4), plan upgrade to 2.0.4 or later
  4. 4. Review release notes for the target version at www.dnsdist.org for any relevant changes
  5. 5. Test the upgrade in a non-production environment first
  6. 6. Backup current configuration files
  7. 7. Stop the dnsdist service
  8. 8. Install the fixed version (1.9.13 or 2.0.4) using your system's package manager or from source
Caveat Check release notes for any breaking changes between your current version and the target fixed version; major version upgrades (e.g., 1.x to 2.x) may introduce behavioral changes

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

Fix this in Dnsdist Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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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-2026-33599 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