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RecursorApplication · Powerdns

CVE-2019-3807

CRITICAL · 9.8 CVSS v3.0 Published 2019-01-29
Fix available
A fix is available. Upgrade to after 4.1.8 or later.
See remediation →
100/100
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
An issue has been found in PowerDNS Recursor versions 4.1.x before 4.1.9 where records in the answer section of responses received from authoritative servers with the AA flag not set were not properly validated, allowing an attacker to bypass DNSSEC validation.

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 · high confidence

DNSSEC validation bypass vulnerability in PowerDNS Recursor 4.1.x before 4.1.9. When the recursor receives DNS responses from authoritative servers where the AA (Authoritative Answer) flag is not set, it fails to properly validate records in the answer section, allowing attackers to craft malicious responses that bypass DNSSEC signature verification.

MitigationUpgrade PowerDNS Recursor to version 4.1.9 or later to obtain the fix. Prioritize patching public-facing resolvers given the critical severity and the potential for DNS cache poisoning attacks.

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
RecursorApplication
Affected:>= 4.1.0, <= 4.1.8

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
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 Recursor version
    Run 'rec_control version' or check the package version with 'dpkg -l pdns-recursor' (Debian/Ubuntu) or 'rpm -q pdns-recursor' (RHEL/CentOS)
    Affected if Version is between 4.1.0 and 4.1.8 inclusive
  2. Verify DNSSEC validation is enabled
    Check the recursor configuration file (typically /etc/pdns-recursor.conf) for 'dnssec=validate' or 'dnssec=log-failed' setting, or run 'rec_control get dnssec'
    Affected if DNSSEC validation mode is set to 'validate' or 'log-failed' (bypass only occurs when DNSSEC processing is active)
  3. Confirm the recursor is processing recursive queries
    Review logs or check if the service is binding to port 53 and accepting recursive queries from clients
    Affected if The recursor is operating as a caching resolver accepting queries from end clients (authoritative-only mode is not affected)
  4. Check for AA flag handling in recent logs
    Examine /var/log/pdns-recursor.log or journalctl -u pdns-recursor for DNS response patterns; look for answer sections from non-authoritative servers
    Affected if The recursor is receiving responses from upstream authoritative servers where the AA flag is unset (this is the trigger condition for the bypass)

You are affected if running PowerDNS Recursor 4.1.0-4.1.8 with DNSSEC validation enabled and acting as a caching resolver that processes recursive queries from clients.

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 a release after 4.1.8
Interim mitigation

Upgrade PowerDNS Recursor to version 4.1.9 or later to obtain the fix. Prioritize patching public-facing resolvers given the critical severity and the potential for DNS cache poisoning attacks.

Recommended fix High confidence

PowerDNS Recursor 4.1.9 or later

  1. 1. Identify current PowerDNS Recursor version by running 'rec_control version' or checking the package version
  2. 2. Review the PowerDNS Recursor 4.1.9 release notes for any migration notes or configuration changes
  3. 3. Plan a maintenance window for the upgrade
  4. 4. Upgrade PowerDNS Recursor to version 4.1.9 or later using your distribution's package manager or from source
  5. 5. After upgrade, restart the Recursor service
  6. 6. Verify the new version is running with 'rec_control version'
  7. 7. Test DNS resolution and confirm DNSSEC validation is working correctly

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

Fix this in Recursor Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.

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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-2019-3807 in production — separate from our analysis above.

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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