FedoraOperating system · Fedoraproject
CVE-2022-3204
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 · uneditedA vulnerability named 'Non-Responsive Delegation Attack' (NRDelegation Attack) has been discovered in various DNS resolving software. The NRDelegation Attack works by having a malicious delegation with a considerable number of non responsive nameservers. The attack starts by querying a resolver for a record that relies on those unresponsive nameservers. The attack can cause a resolver to spend a lot of time/resources resolving records under a malicious delegation point where a considerable number of unresponsive NS records reside. It can trigger high CPU usage in some resolver implementations that continually look in the cache for resolved NS records in that delegation. This can lead to degraded performance and eventually denial of service in orchestrated attacks. Unbound does not suffer from high CPU usage, but resources are still needed for resolving the malicious delegation. Unbound will keep trying to resolve the record until hard limits are reached. Based on the nature of the attack and the replies, different limits could be reached. From version 1.16.3 on, Unbound introduces fixes for better performance when under load, by cutting opportunistic queries for nameserver discovery and DNSKEY prefetching and limiting the number of times a delegation point can issue a cache lookup for missing records.
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 confidenceThe NRDelegation Attack exploits DNS resolver behavior by creating malicious delegations containing numerous unresponsive nameservers. When a resolver attempts to resolve records under such delegations, it repeatedly queries and caches lookups for missing NS records, consuming excessive resources and causing denial of service. Unbound versions prior to 1.16.3 are vulnerable as they lack limits on opportunistic queries and cache lookups for delegation points.
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
FedoraOperating system
= 35= 36= 37<= 1.16.2CVSS 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 the installed Unbound versionRun 'unbound -V' or 'unbound-control version' to retrieve the installed version numberAffected if The version is 1.16.2 or earlier, or the specific version cannot be determined but the package is from a distribution that ships vulnerable versions
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Confirm Unbound is configured as a resolverInspect the unbound.conf configuration file (typically in /etc/unbound/ or /etc/unbound/conf.d/) and check for 'forward-zone' or 'local-zone' directives, or check if the service is running and accepting recursive queriesAffected if Unbound is configured to perform recursive resolution or forward DNS queries (the vulnerability applies to resolver operations)
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Check the operating system if using a distribution packageRun 'cat /etc/fedora-release' or 'cat /etc/os-release' to identify the Fedora versionAffected if The system runs Fedora 35, Fedora 36, or Fedora 37 (these distributions ship Unbound versions that are vulnerable)
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Verify the package version from distribution repositoriesRun 'rpm -qa | grep unbound' or 'dnf list installed unbound' to check the packaged version of Unbound installed via the distributionAffected if The installed package version is lower than the fixed version (1.16.3) or was shipped by a vulnerable Fedora release
You are affected if Unbound version 1.16.2 or earlier is installed and configured as a DNS resolver, or if running Fedora 35, 36, or 37 with the distribution-supplied Unbound package.
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 · scopedUpgrade Unbound to version 1.16.3 or later, which implements fixes that cut opportunistic nameserver discovery and DNSKEY prefetching while limiting the number of cache lookups for missing delegation records.
Unbound >= 1.16.3
- Upgrade Unbound to version 1.16.3 or later. This version contains fixes that cut opportunistic queries for nameserver discovery and DNSKEY prefetching, and limits the number of times a delegation point can issue a cache lookup for missing records.
- After upgrading, verify the version to confirm the fix is applied.
- Test the resolver to ensure normal DNS resolution functionality is maintained.
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Fedora
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2022-3204 — 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-2022-3204 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
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