CVE-2026-45557
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 · uneditedTechnitium DNS Server aggressively tries to fetch missing RRSIG records or mismatched DNSKEY records. An attacker in control of a domain can cause a vulnerable system to generate excessive network traffic. Fixed in 15.0.
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 confidenceTechnitium DNS Server has a flaw where it aggressively attempts to fetch missing RRSIG records or mismatched DNSKEY records during DNSSEC validation. An attacker controlling a malicious domain can trigger this behavior, causing the vulnerable DNS server to generate excessive outbound network traffic as it repeatedly attempts to fetch records that don't exist or have mismatched keys.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- Changed
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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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Confirm Technitium DNS Server is installedLook for the Technitium DNS Server process in running services or check installed programs. On Linux, run 'systemctl status technitium-dns' or check for the DNS server process.Affected if Technitium DNS Server is found running on the system
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Identify the installed versionAccess the DNS server web admin panel (typically port 5380) and check the version displayed in the dashboard, or check the installed package version using system package managers.Affected if The installed version is lower than 15.0
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Verify DNSSEC validation is enabledIn the web admin panel, go to 'DNSSEC' settings and check if DNSSEC validation is turned on. On config files, look for 'enableDnssec' or similar DNSSEC-related configuration options.Affected if DNSSEC validation is enabled and version is below 15.0
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Check for excessive outbound DNS trafficMonitor network traffic using tools like tcpdump or Wireshark on the DNS server's external interface. Look for a high volume of outgoing DNS queries, particularly to authoritative nameservers for domains the server is validating.Affected if The server is generating unusually high outbound DNS traffic to external authoritative servers
A user is affected if they are running Technitium DNS Server version below 15.0 with DNSSEC validation enabled, and they observe or have historically observed excessive outbound DNS traffic patterns.
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 Technitium DNS Server to version 15.0 or later to obtain the patch. If immediate upgrading is not feasible, consider implementing query rate limiting or monitoring for anomalous DNS query volumes.
Technitium DNS Server 15.0
- 1. Backup the current Technitium DNS Server configuration and data
- 2. Stop the Technitium DNS Server service
- 3. Download Technitium DNS Server version 15.0 or later from the official GitHub releases page (github.com/TechnitiumSoftware/DnsServer)
- 4. Install the updated version following standard upgrade procedures
- 5. Verify the service starts successfully
- 6. Test DNS resolution functionality to confirm normal operation
- 7. Monitor network traffic patterns to verify the fix is effective
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 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-2026-45557 — 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-2026-45557 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
- No spam, self-promotion, credentials, or personal data