Joomla\!Application · Joomla
CVE-2019-12766
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 issue was discovered in Joomla! before 3.9.7. The subform fieldtype does not sufficiently filter or validate input of subfields. This leads to XSS attack vectors.
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 confidenceJoomla! before version 3.9.7 contains a stored Cross-Site Scripting (XSS) vulnerability in the subform fieldtype component. The field does not properly sanitize or validate input of subfields, allowing authenticated attackers to inject malicious scripts that execute in the browsers of other users viewing the affected content.
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
Joomla\!Application
>= 3.6.0, <= 3.9.6CVSS 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
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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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Determine Joomla! versionLog into the Joomla! administrator dashboard and navigate to System > System Information, or check the libraries/cms.php file for the VERSION constantAffected if The installed version is between 3.6.0 and 3.9.6 inclusive
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Identify subform field usageSearch the Joomla! database in the #__fields table for field types set to 'subform', or review custom field configurations that use the subform fieldtypeAffected if Any custom fields are configured with the subform fieldtype component
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Inspect subform field content for malicious scriptsQuery the #__fields_values table for any field_id associated with subform fields, examining the value column for script tags or javascript: URIsAffected if The stored values contain unsanitized HTML script tags or event handler attributes
You are affected if your Joomla! installation version is 3.6.0 through 3.9.6 AND you have custom fields using the subform fieldtype with potentially unsanitized content in the stored values.
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 dataUpgrade Joomla! to version 3.9.7 or later, which contains the fix for proper input filtering and validation in the subform fieldtype.
Fix this in Joomla\!
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 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-2019-12766 — 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-2019-12766 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