FirefoxWeb browser · Mozilla
CVE-2019-9816
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 · uneditedA possible vulnerability exists where type confusion can occur when manipulating JavaScript objects in object groups, allowing for the bypassing of security checks within these groups. *Note: this vulnerability has only been demonstrated with UnboxedObjects, which are disabled by default on all supported releases.*. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.
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 confidenceType confusion vulnerability in SpiderMonkey JavaScript engine allowing security check bypass within object groups. Exploitation requires UnboxedObjects to be enabled, which is disabled by default in affected versions.
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
< 67.0
Firefox EsrWeb browser
< 60.7< 60.7CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
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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Identify the installed Firefox versionOpen Firefox, click the menu button, select Help, then About Firefox. The version number is displayed on this page.Affected if the version displayed is below 67.0 (for example, 66.x or earlier)
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Identify the installed Firefox ESR versionOpen Firefox ESR, click the Help menu, select About Mozilla Firefox. The version number is displayed.Affected if the version displayed is below 60.7 (for example, 60.6.x or earlier)
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Identify the installed Thunderbird versionOpen Thunderbird, click the Help menu, select About Thunderbird. The version number is displayed.Affected if the version displayed is below 60.7 (for example, 60.6.x or earlier)
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Verify UnboxedObjects configuration in FirefoxIn the Firefox address bar, type about:config and press Enter. In the search field, type "unboxed.objects". Check if the preference exists and what its value is.Affected if the preference value is set to true (enabled). Note: This setting is disabled by default in affected versions.
A user is affected only if they are running a vulnerable version (Firefox < 67.0, Firefox ESR < 60.7, or Thunderbird < 60.7) AND have manually enabled the UnboxedObjects setting in about:config.
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.
From vendor data60.767.0
Update to Firefox 67, Thunderbird 60.7, Firefox ESR 60.7 or later. Ensure UnboxedObjects remain disabled as a defense-in-depth measure.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 h
- Testing1.0 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 $1,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-9816 — 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-2019-9816 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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