NeqoApplication · Mozilla
CVE-2025-6703
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 · uneditedImproper Input Validation vulnerability in Mozilla neqo leads to an unexploitable crash..This issue affects neqo: from 0.4.24 through 0.13.2.
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 confidenceImproper input validation in Mozilla's neqo QUIC library allows specially crafted network input to cause a crash. The vendor classifies this as unexploitable (not leading to code execution), but it creates a denial-of-service condition via crash. Affected versions range from 0.4.24 through 0.13.2.
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
NeqoApplication
>= 0.4.24, <= 0.13.2CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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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Locate neqo in your environmentIdentify where neqo is used - check Cargo.toml dependencies, Cargo.lock for Rust projects, or any binaries/services that incorporate the neqo libraryAffected if neqo library or a product using it is present in your environment
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Determine the installed neqo versionCheck Cargo.toml or Cargo.lock for the neqo version, or run the application with --version or -V flags if availableAffected if the reported version is 0.4.24 through 0.13.2 (inclusive)
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Confirm QUIC processing is enabledVerify that your application or service actually processes QUIC network traffic using neqo - check if QUIC listeners or connections are configured and activeAffected if QUIC functionality with neqo is actively processing incoming network data
You are affected if neqo version 0.4.24 through 0.13.2 is installed AND your environment processes QUIC traffic with this library, as malformed QUIC packets can trigger a crash.
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 · scopedUpdate to a fixed version of neqo beyond 0.13.2, or apply input validation hardening to the parsing code paths to prevent crash conditions from malformed QUIC data.
neqo version 0.13.3 or later
- 1. Identify the current neqo version in use by checking Cargo.toml, package.json, or running the application's version command
- 2. Update the neqo dependency to version 0.13.3 or later in your dependency manifest (e.g., Cargo.toml)
- 3. Run dependency update command (e.g., cargo update or cargo upgrade) to fetch the fixed version
- 4. Rebuild and test the application to verify the crash no longer occurs
- 5. Deploy the updated application
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Neqo
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-6703 — 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-2025-6703 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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