FirefoxWeb browser · Mozilla
CVE-2023-25736
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 invalid downcast from `nsHTMLDocument` to `nsIContent` could have lead to undefined behavior. This vulnerability affects Firefox < 110.
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 confidenceA type safety vulnerability in Mozilla Firefox's Gecko engine allows an invalid downcast from nsHTMLDocument to nsIContent, leading to undefined behavior. This C++ type confusion could be exploited for arbitrary code execution.
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
FirefoxWeb browser
< 110.0CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 installed Firefox versionOpen Firefox, go to Help > About Firefox, or navigate to about:support, or run 'firefox --version' from command lineAffected if Version displayed is below 110.0 (e.g., 109.x, 108.x, etc.)
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Verify Gecko engine versionNavigate to about:support in Firefox and locate the 'Graphics' section or 'GeckoView' entry if presentAffected if Gecko version corresponds to a Firefox release prior to 110.0
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Check Windows registry for Firefox versionRun 'reg query "HKLM\SOFTWARE\Mozilla\Mozilla Firefox" /v CurrentVersion' in Command PromptAffected if Returned version is less than 110.0
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Check macOS Firefox versionRun 'defaults read /Applications/Firefox.app/Contents/Info CFBundleShortVersionString' in TerminalAffected if Version string is below 110.0
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Check Linux package versionRun 'firefox --version' or check package manager: 'dpkg -l firefox' (Debian/Ubuntu) or 'rpm -q firefox' (RHEL/Fedora)Affected if Package version is earlier than 110.0
A system is affected if Firefox is installed and the detected version is any release prior to version 110.0.
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 · scoped110.0
Update Firefox to version 110 or later. For enterprise environments, deploy the browser update via patch management infrastructure and verify successful installation across all affected endpoints.
Firefox 110.0
- 1. Open Firefox and navigate to Menu > Help > About Firefox
- 2. The About Firefox window will automatically check for updates
- 3. If an update is available, download and install Firefox 110.0 or later
- 4. Restart Firefox to complete the update
- 5. Verify the version by checking Menu > Help > About Firefox shows version 110.0 or higher
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 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 $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-25736 — 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-2023-25736 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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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.
- 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