Joomla\!Application · Joomla
CVE-2026-48954
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 validation leads to a generic XSS vector in the language override feature.
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 confidenceA Cross-Site Scripting (XSS) vulnerability exists in the language override feature due to improper input validation. The vulnerability allows an attacker to inject malicious scripts through the language override mechanism, potentially compromising user sessions or executing arbitrary JavaScript in the context of other users.
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
>= 3.0.0, < 5.4.7>= 6.0.0, < 6.1.2CVSS 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
- 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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Check your Joomla versionNavigate to Administrator dashboard > System > Information or check the version.php file in your Joomla root/includes folderAffected if The installed version is >= 3.0.0 and < 5.4.7, OR >= 6.0.0 and < 6.1.2
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Identify if language overrides are in useCheck for custom language override files in your installation. These are typically stored in the /language/overrides/ directory (for Joomla 3.x) or /administrator/language/overrides/ (for Joomla 4/5/6). Look for .ini files with non-standard naming or recently modified dates.Affected if Custom language override files exist in the overrides directory
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Inspect language override files for unsanitized contentOpen the language override .ini files in a text editor and examine the string values on the right side of each KEY=VALUE pair. Look for JavaScript tags, event handlers (onclick, onerror, etc.), or other suspicious script-like patterns.Affected if Any language override string contains unescaped HTML tags, script elements, or javascript: protocols
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Check for recently modified overridesReview file modification timestamps on language override files. Compare against any timeline of suspicious administrative activity.Affected if Language override files were modified unexpectedly or contain content you did not create
You are affected if your Joomla version falls within the vulnerable ranges AND you have custom language overrides that contain malicious script content.
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 · scoped5.4.76.1.2
Implement proper input validation and output encoding for the language override feature, specifically sanitizing all user-supplied language strings before storage and before rendering.
Joomla! 5.4.7+ or Joomla! 6.1.2+ (depending on your major version branch)
- 1. Back up your Joomla! database and files before proceeding with the upgrade
- 2. Review the Joomla! official upgrade documentation at developer.joomla.org for your specific version
- 3. For Joomla! 5.x (versions 3.0.0 to 5.4.6): Upgrade to Joomla! 5.4.7 or later
- 4. For Joomla! 6.x (versions 6.0.0 to 6.1.1): Upgrade to Joomla! 6.1.2 or later
- 5. After upgrading, verify the language override feature functions correctly
- 6. Test that the XSS vulnerability is remediated by attempting to inject script content in language overrides
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Joomla\!
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 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 $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-48954 — 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-2026-48954 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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