FirefoxWeb browser · Mozilla
CVE-2020-15664
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 · uneditedBy holding a reference to the eval() function from an about:blank window, a malicious webpage could have gained access to the InstallTrigger object which would allow them to prompt the user to install an extension. Combined with user confusion, this could result in an unintended or malicious extension being installed. This vulnerability affects Firefox < 80, Thunderbird < 78.2, Thunderbird < 68.12, Firefox ESR < 68.12, Firefox ESR < 78.2, and Firefox for Android < 80.
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 reference to the eval() function from an about:blank window provides access to the InstallTrigger object, enabling a malicious webpage to prompt users to install extensions. Combined with social engineering, this could lead to unintended or malicious extension installation.
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
< 80.0>= 78.0, < 78.2
Firefox EsrWeb browser
< 68.12< 68.12>= 78.0, < 78.2CVSS 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
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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 installed Mozilla productCheck if Firefox, Firefox ESR, or Thunderbird is installed by looking for the executable or checking the application name/version in the systemAffected if Any of the affected products (Firefox, Firefox ESR, Thunderbird) are installed
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Determine Firefox versionIn Firefox, go to Menu > Help > About Firefox to display the version number. Alternatively, check the application file properties or use command: firefox --versionAffected if Version is < 80.0 OR (>= 78.0 AND < 78.2)
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Determine Firefox ESR versionIn Firefox ESR, go to Menu > Help > About Firefox ESR. Alternatively, check the application file propertiesAffected if Version is < 68.12
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Determine Thunderbird versionIn Thunderbird, go to Menu > Help > About Thunderbird. Alternatively, check the application file propertiesAffected if Version is < 68.12 OR (>= 78.0 AND < 78.2)
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Verify about:blank context vulnerabilityOpen a new tab to about:blank, open browser console, and attempt to access: var w = window.open('about:blank'); w.eval('InstallTrigger'). If InstallTrigger object is accessible, the vulnerability is presentAffected if The InstallTrigger object is accessible from an about:blank window context via eval()
You are affected if you run any version of Firefox < 80.0 (or 78.0-78.1), Firefox ESR < 68.12, or Thunderbird < 68.12 (or 78.0-78.1) AND the InstallTrigger object is accessible from about:blank windows.
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 data68.1278.280.0
Update affected Mozilla products to Firefox 80+, Thunderbird 78.2+, Thunderbird 68.12+, Firefox ESR 68.12+, Firefox ESR 78.2+, or Firefox for Android 80+ to patch this vulnerability.
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-2020-15664 — 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-2020-15664 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