CVE-2025-30194
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 · uneditedWhen DNSdist is configured to provide DoH via the nghttp2 provider, an attacker can cause a denial of service by crafting a DoH exchange that triggers an illegal memory access (double-free) and crash of DNSdist, causing a denial of service. The remedy is: upgrade to the patched 1.9.9 version. A workaround is to temporarily switch to the h2o provider until DNSdist has been upgraded to a fixed version. We would like to thank Charles Howes for bringing this issue to our attention.
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 confidenceDNSdist versions prior to 1.9.9 contain a double-free vulnerability in the nghttp2-based DNS-over-HTTPS (DoH) provider. An attacker can trigger this by sending specially crafted DoH requests that cause illegal memory access, resulting in a crash and denial of service.
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
- 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 DNSdist is installedRun 'dnsdist --version' or check for the dnsdist binary in /usr/sbin/dnsdist or /usr/bin/dnsdistAffected if dnsdist binary is not found, meaning the product is not present
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Check the installed DNSdist versionRun 'dnsdist --version' and compare the version number to 1.9.9Affected if the reported version is lower than 1.9.9 (e.g., 1.9.8, 1.9.0, etc.)
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Determine if DoH with nghttp2 is configuredReview the dnsdist configuration file (typically /etc/dnsdist.conf or /etc/dnsdist/dnsdist.conf) and look for addDOH(), DOHFrontend(), or similar DoH-related configuration lines. Check if the provider is set to nghttp2 or if no explicit provider is specified (defaults to nghttp2 in affected versions)Affected if DoH is configured using the nghttp2 provider (or using default settings where nghttp2 is the default) on a version prior to 1.9.9
A defender is affected if they are running DNSdist version 1.9.8 or lower AND have DNS-over-HTTPS enabled with the nghttp2 provider configured.
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 DNSdist to version 1.9.9 or later to patch the double-free vulnerability. As a temporary workaround, switch the DoH provider from nghttp2 to h2o until the upgrade can be performed.
dnsdist version 1.9.9
- Upgrade dnsdist to version 1.9.9 or later to resolve the use-after-free vulnerability in the nghttp2 DoH provider.
- If immediate upgrade is not possible, temporarily configure dnsdist to use the h2o provider instead of nghttp2 for DNS-over-HTTPS until the upgrade can be performed.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 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 $2,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-30194 — 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-2025-30194 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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- Version or environment caveats, and links to real fixes
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