CVE-2020-25829
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 · uneditedAn issue has been found in PowerDNS Recursor before 4.1.18, 4.2.x before 4.2.5, and 4.3.x before 4.3.5. A remote attacker can cause the cached records for a given name to be updated to the Bogus DNSSEC validation state, instead of their actual DNSSEC Secure state, via a DNS ANY query. This results in a denial of service for installation that always validate (dnssec=validate), and for clients requesting validation when on-demand validation is enabled (dnssec=process).
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 confidenceA remote attacker can send a DNS ANY query to PowerDNS Recursor, causing cached records to be stored with an incorrect DNSSEC validation state (Bogus instead of Secure). This cache poisoning effectively breaks DNSSEC validation for affected domains, causing DoS for installations using dnssec=validate or dnssec=process modes.
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< 4.1.18>= 4.2.0, < 4.2.5>= 4.3.0, < 4.3.5= 15.0= 15.1= 15.2CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify PowerDNS Recursor versionRun 'rec_control version' or check package manager (dpkg -r pdns-recursor, rpm -q pdns-recursor)Affected if version is < 4.1.18, OR >= 4.2.0 and < 4.2.5, OR >= 4.3.0 and < 4.3.5
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Locate PowerDNS Recursor configuration fileCommon paths: /etc/pdns-recursor/recursor.conf or /etc/recursor.confAffected if configuration file exists indicating PowerDNS Recursor is in use
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Check DNSSEC validation mode settingGrep for 'dnssec' in the recursor.conf file: grep -E '^dnssec=' /etc/pdns-recursor/recursor.confAffected if dnssec is set to 'validate' or 'process' (values that perform DNSSEC validation)
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Verify running service statusCheck if pdns-recursor service is running: systemctl status pdns-recursor or ps aux | grep pdns-recursorAffected if service is running with an affected version AND dnssec validation is enabled
You are affected if PowerDNS Recursor is running with a vulnerable version AND DNSSEC validation mode (validate or process) is enabled, allowing DNS ANY queries to poison the cache with incorrect DNSSEC status.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor data4.1.184.2.54.3.5
Upgrade PowerDNS Recursor to version 4.1.18, 4.2.5, 4.3.5 or later. Until patched, consider reducing dnssec validation mode or implementing additional monitoring for validation failures.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2020-25829 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-25829 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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