CVE-2026-0398
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 · uneditedCrafted zones can lead to increased resource usage and crafted CNAME chains can lead to cache poisoning in Recursor.
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 confidenceThis vulnerability in the PowerDNS Recursor allows remote attackers to cause increased resource usage through crafted DNS zones, leading to potential denial of service. Additionally, specially crafted CNAME record chains can be exploited for cache poisoning attacks, enabling attackers to inject malicious DNS records into the resolver's cache.
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>= 5.1.0, < 5.1.10>= 5.2.8, < 5.2.8>= 5.3.0, < 5.3.5CVSS 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
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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 the package version with 'dpkg -l pdns-recursor' (Debian/Ubuntu) or 'rpm -q pdns-recursor' (RHEL/CentOS)Affected if Version falls within 5.1.0-5.1.9, 5.2.8, or 5.3.0-5.3.4
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Confirm Recursor service is runningRun 'systemctl status pdns-recursor' or 'rec_control get pid'Affected if Service is running and serving DNS queries
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Check for elevated query load patternsMonitor query counts via 'rec_control get all-queries' over time, or review logs for sudden spikes in CNAME-related queriesAffected if Unusual spike in CNAME chain queries or DNS query volume from untrusted zones
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Inspect DNS cache for suspicious CNAME chainsUse 'rec_control get-cache-entries' and review cached records; check for unexpectedly long or unexpected CNAME chains pointing to malicious domainsAffected if Cache contains unusually long CNAME chains or suspicious resolved records pointing to untrusted domains
The environment is affected if PowerDNS Recursor version is 5.1.0-5.1.9, 5.2.8, or 5.3.0-5.3.4 and the service is processing DNS queries from potentially malicious sources.
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.
dbcve · scoped5.1.105.2.85.3.5
Upgrade PowerDNS Recursor to the latest patched version as specified in the vendor security advisory. Review DNS zone configurations and monitor for unusual CNAME chain patterns.
Recursor 5.1.10+, 5.2.9+, or 5.3.5+ (choose the appropriate branch)
- 1. Identify current PowerDNS Recursor version using 'rec_control version' or 'pdns_recursor --version'
- 2. For Recursor 5.1.x: upgrade to version 5.1.10 or later
- 3. For Recursor 5.2.8: upgrade to version 5.2.9 or later (first version after 5.2.8)
- 4. For Recursor 5.3.x: upgrade to version 5.3.5 or later
- 5. After upgrade, verify the running version matches the expected fixed version
- 6. Monitor resource usage and DNS cache integrity post-upgrade to confirm remediation
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-0398 — 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-2026-0398 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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- 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
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