dbcve.org
DnsserverApplication · Technitium

CVE-2023-49203

HIGH · 7.5 CVSS v3.1 Published 2024-09-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
Technitium 11.5.3 allows remote attackers to cause a denial of service (bandwidth amplification) because the DNSBomb manipulation causes accumulation of low-rate DNS queries such that there is a large-sized response in a burst of traffic.

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 confidence

Technitium DNS Server 11.5.3 is vulnerable to a bandwidth amplification DoS attack using the DNSBomb technique. Attackers send low-rate DNS queries that accumulate on the server, which then triggers a large burst of amplified responses, overwhelming target resources.

MitigationImplement query rate limiting and response size throttling on the DNS server to prevent query accumulation and limit response burst sizes. Consider applying any available vendor patches for Technitium DNS Server.

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
DnsserverApplication
Affected:= 11.5.3

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
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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify Technitium DNS Server version
    Check the installed version of Technitium DNS Server. On Windows, check the program's version property in Control Panel > Programs and Features, or check the DnsServer.exe file properties. On Linux, check the package version or run 'dns-server --version' if available.
    Affected if The installed version is exactly 11.5.3
  2. Verify DNS service is running
    Confirm the Technitium DNS Server service is active and listening on DNS port 53 (typically UDP/TCP). Use command: 'netstat -anp | grep :53' on Linux or check Services snap-in on Windows.
    Affected if The DNS service is running and exposed on port 53 while version 11.5.3 is installed
  3. Check for query rate limiting configuration
    Inspect the DNS server configuration files (config.json or settings web UI) for 'rateLimit' or 'queryRateLimit' settings. Look for any rate limiting rules that control how many queries can accumulate before triggering burst responses.
    Affected if No rate limiting is configured and the server is version 11.5.3, meaning queries can accumulate without restriction
  4. Check response size throttling settings
    Examine DNS server settings for any 'maxResponseSize', 'responseThrottle', or 'edns' configuration options that limit the size of DNS responses sent to clients.
    Affected if Response size throttling is not configured, allowing large amplified responses to be sent from accumulated queries

You are affected if Technitium DNS Server version 11.5.3 is installed and running with no rate limiting or response throttling configured, allowing query accumulation and amplified response bursts.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement query rate limiting and response size throttling on the DNS server to prevent query accumulation and limit response burst sizes. Consider applying any available vendor patches for Technitium DNS Server.

Recommended fix Moderate confidence

Technitium DNS Server 11.5.4 or latest stable release

  1. 1. Backup your current Technitium DNS Server configuration and data.
  2. 2. Download the latest stable version of Technitium DNS Server from the official download page at technitium.com/downloads/.
  3. 3. Install or update to the latest version (verify version is 11.5.4 or later which contains the DNSBomb fix).
  4. 4. After upgrade, verify the DNS server is running correctly and responding to queries.
  5. 5. Monitor logs for any unusual amplification patterns to confirm the fix is effective.
Caveat Review release notes for any configuration changes between 11.5.3 and the target version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Dnsserver Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-49203 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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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