dbcve.org
MediawikiCMS

CVE-2021-46146

MEDIUM · 5.4 CVSS v3.1 Published 2022-01-10
Fix available
A fix is available. Upgrade to 1.35.5 / 1.36.3 or later.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

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 · unedited
An issue was discovered in MediaWiki before 1.35.5, 1.36.x before 1.36.3, and 1.37.x before 1.37.1. The WikibaseMediaInfo component is vulnerable to XSS via the caption fields for a given media file.

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 confidence

Cross-site scripting (XSS) vulnerability in the WikibaseMediaInfo component of MediaWiki allows injection of malicious scripts through caption fields for media files. When users view affected media files, the unsanitized caption content executes in their browsers.

MitigationUpdate MediaWiki to version 1.35.5, 1.36.3, 1.37.1 or later to obtain the patch that properly sanitizes caption field input.

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
MediawikiCMS
Affected:< 1.35.5>= 1.36.0, < 1.36.3>= 1.37.0, < 1.37.1

CVSS 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
Low
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify MediaWiki installation
    Locate your MediaWiki installation directory or access Special:Version page on your wiki
    Affected if MediaWiki is present
  2. Determine MediaWiki version
    Check the version in includes/Defines.php file or view Special:Version. Compare against affected ranges: < 1.35.5, >= 1.36.0 but < 1.36.3, >= 1.37.0 but < 1.37.1
    Affected if Installed version falls within any of these three ranges
  3. Verify WikibaseMediaInfo extension is enabled
    Check LocalSettings.php for 'WikibaseMediaInfo' inclusion or view Special:Version page to confirm the extension is listed
    Affected if WikibaseMediaInfo extension is installed and enabled
  4. Check if caption editing is accessible
    Verify users can access media file caption fields through the upload or media viewing interface
    Affected if Caption fields for media files are accessible to users

You are affected if your MediaWiki version is one of the vulnerable versions AND the WikibaseMediaInfo extension with caption functionality is enabled in your environment.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to 1.35.5 / 1.36.3 / 1.37.1 or later
Fixed in 1.35.51.36.31.37.1
Interim mitigation

Update MediaWiki to version 1.35.5, 1.36.3, 1.37.1 or later to obtain the patch that properly sanitizes caption field input.

Recommended fix High confidence

1.35.5, 1.36.3, or 1.37.1 (or later stable release)

  1. 1. Identify your current MediaWiki version by checking the $wgVersion variable in includes/DefaultSettings.php or the Special:Version page
  2. 2. Determine which upgrade path suits your current version: upgrade to 1.35.5+ if on 1.35.x, upgrade to 1.36.3+ if on 1.36.x, or upgrade to 1.37.1+ if on 1.37.x
  3. 3. Create a full backup of your MediaWiki database and files before proceeding
  4. 4. Download the appropriate fixed release from https://www.mediawiki.org/wiki/Download
  5. 5. Replace your existing MediaWiki files with the new version, preserving your LocalSettings.php and any custom configuration
  6. 6. Run the maintenance/update.php script to update the database schema if needed
  7. 7. Clear any caching systems (including PHP opcache and any CDN caches)
  8. 8. Verify the upgrade by checking Special:Version shows the correct version number
Caveat Standard minor version upgrades typically don't introduce breaking changes, but always review the release notes for your target version and test in a staging environment before production deployment

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Mediawiki Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-46146 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-46146 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

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.

What belongs here
  • 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