CVE-2023-28450
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 · uneditedAn issue was discovered in Dnsmasq before 2.90. The default maximum EDNS.0 UDP packet size was set to 4096 but should be 1232 because of DNS Flag Day 2020.
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 confidenceDnsmasq before version 2.90 configured a default maximum EDNS.0 UDP packet size of 4096 bytes instead of the DNS Flag Day 2020 recommended 1232 bytes. This oversized buffer can cause UDP packet fragmentation, increasing attack surface for DNS-based denial of service or exploitation via large malformed packets.
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< 2.90CVSS 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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Check if Dnsmasq is installed and get its versionRun `dnsmasq --version` or `dnsmasq -v` to display the installed version numberAffected if The displayed version is below 2.90 (e.g., 2.89, 2.88, etc.)
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Locate Dnsmasq configuration filesCheck common config locations: /etc/dnsmasq.conf, /etc/dnsmasq.d/*.conf, /etc/dnsmasq.d/*.conf, or run `dnsmasq --conf-file --conf-dir` to list loaded config filesAffected if No configuration file is found or the configuration directory is empty
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Check for explicit max-udpsize settingSearch config files for the `max-udpsize` directive using `grep -r "max-udpsize" /etc/dnsmasq*`Affected if The directive is absent AND the installed version is below 2.90, meaning the default 4096-byte buffer is in use
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Verify the active EDNS.0 UDP buffer size at runtimeRun `dnsmasq --test` to validate config, then check running process with `ps aux | grep dnsmasq` and inspect `/proc/<pid>/cmdline` for runtime parameters, or query DNS with `dig +short +time=1 +tries=1 +edns=0 @127.0.0.1 . SOA` and observe the OPT recordAffected if No explicit max-udpsize parameter is passed at runtime AND version is below 2.90, indicating the vulnerable 4096-byte default is active
You are affected if Dnsmasq version is below 2.90 AND no `max-udpsize=1232` (or similar value) is explicitly configured, as the default 4096-byte buffer will be used.
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 · scoped2.90
Upgrade Dnsmasq to version 2.90 or later, or manually set max-udpsize=1232 in the dnsmasq configuration file to comply with DNS Flag Day 2020 recommendations.
Dnsmasq 2.90
- 1. Check current Dnsmasq version using 'dnsmasq --version' or your package manager
- 2. Upgrade Dnsmasq to version 2.90 or later from your distribution's package repository or thekelleys.org.uk
- 3. Restart the Dnsmasq service after upgrade
- 4. Verify the new version is running using 'dnsmasq --version'
Generated from the published advisory — verify against the referenced sources before acting.
- 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-2023-28450 — 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-2023-28450 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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