FedoraOperating system · Fedoraproject
CVE-2020-10995
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 · uneditedPowerDNS Recursor from 4.1.0 up to and including 4.3.0 does not sufficiently defend against amplification attacks. An issue in the DNS protocol has been found that allow malicious parties to use recursive DNS services to attack third party authoritative name servers. The attack uses a crafted reply by an authoritative name server to amplify the resulting traffic between the recursive and other authoritative name servers. Both types of service can suffer degraded performance as an effect. This is triggered by random subdomains in the NSDNAME in NS records. PowerDNS Recursor 4.1.16, 4.2.2 and 4.3.1 contain a mitigation to limit the impact of this DNS protocol issue.
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 confidencePowerDNS Recursor versions 4.1.0-4.3.0 insufficiently defend against DNS amplification attacks. Malicious authoritative name servers can exploit crafted replies with random subdomains in NSDNAME fields to amplify traffic between recursive resolvers and authoritative servers, causing degraded performance.
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
= 31= 32
Debian LinuxOperating system
= 10.0>= 4.1.0, <= 4.3.0= 15.0= 15.1CVSS 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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Verify PowerDNS Recursor is installedRun `rpm -q pdns-recursor` (Fedora/openSUSE) or `dpkg -l pdns-recursor` (Debian) to check if the package is installedAffected if Package is not installed means not affected
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Check the installed version numberRun `pdns_recursor --version` or check the package version with `rpm -q --qf '%{VERSION}-%{RELEASE}' pdns-recursor` (Fedora/openSUSE) / `dpkg -s pdns-recursor | grep Version` (Debian)Affected if Version is >= 4.1.0 and <= 4.3.0 indicates vulnerability present
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Confirm the Recursor service is runningRun `systemctl status pdns-recursor` or `ps aux | grep pdns_recursor` to check if the service is activeAffected if Service is running as a recursive resolver means the amplification attack surface is present
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Verify recursive query handling is enabledCheck the configuration file /etc/pdns/recursor.conf (or /etc/pdns-recursor/recursor.conf on Debian) for `allow-recursion` or `recursion` settingsAffected if Recursive lookups are enabled increases exposure to this amplification vector
User is affected if PowerDNS Recursor version 4.1.0 through 4.3.0 is installed and running as an active recursive resolver.
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 dataUpgrade PowerDNS Recursor to version 4.1.16, 4.2.2, or 4.3.1 which contain mitigations to limit the amplification attack impact.
Fix this in Fedora
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-10995 — 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-2020-10995 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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