dbcve.org
MediawikiCMS

CVE-2021-44854

MEDIUM · 5.3 CVSS v3.1 Published 2022-12-26
Fix available
A fix is available. Upgrade to 1.35.5 / 1.36.3 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 REST API publicly caches results from private wikis.

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

The MediaWiki REST API had a caching vulnerability where results from private wikis (requiring authentication) were being cached and made publicly accessible to unauthenticated users. This occurred because the caching mechanism did not properly distinguish between authenticated and unauthenticated requests, allowing private data to leak through the public cache.

MitigationUpgrade to MediaWiki 1.35.5, 1.36.3, 1.37.1 or later, which contain the fix for proper cache key differentiation between private and public wiki responses.

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

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
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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. Check installed MediaWiki version
    View the version number in the admin interface (Special:Version) or check the includes/Defines.php file for the MW_VERSION constant
    Affected if The version is less than 1.35.5, or greater than or equal to 1.36.0 but less than 1.36.3, or equal to 1.37.0
  2. Verify REST API is enabled
    Confirm the REST API endpoint /api/rest_v1/ is accessible, or check LocalSettings.php for $wgRestAPIArray or similar REST configuration
    Affected if The REST API module is enabled and accessible
  3. Confirm caching is active for REST API responses
    Check LocalSettings.php for $wgCacheDirectory, $wgMainCacheType, or any cache configuration related to the REST API. Also verify if a cache backend like Redis, Memcached, or file caching is configured
    Affected if Any form of caching is enabled for the REST API or overall wiki
  4. Identify if wiki has private or authentication-required content
    Review $wgGroupPermissions in LocalSettings.php to see if read access is restricted, or check if authentication extensions are configured for private wikis
    Affected if The wiki contains content that requires authentication to access some or all pages

A user is affected if their MediaWiki version falls within the vulnerable ranges AND the REST API is enabled with caching active AND the wiki has private or restricted content accessible only to authenticated users.

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 or later
Fixed in 1.35.51.36.3
Interim mitigation

Upgrade to MediaWiki 1.35.5, 1.36.3, 1.37.1 or later, which contain the fix for proper cache key differentiation between private and public wiki responses.

Recommended fix High confidence

1.35.5+, 1.36.3+, or 1.37.1+ (choose the appropriate branch)

  1. 1. Identify the current MediaWiki version by checking the includes/Defines.php file or the Special:Version page
  2. 2. If running 1.35.x (version < 1.35.5): Upgrade to MediaWiki 1.35.5 or later (preferably the latest 1.35.x release)
  3. 3. If running 1.36.x (version < 1.36.3): Upgrade to MediaWiki 1.36.3 or later (preferably the latest 1.36.x release)
  4. 4. If running 1.37.0: Upgrade to MediaWiki 1.37.1 or later (preferably the latest 1.37.x release)
  5. 5. After upgrade, verify the REST API no longer caches results from private wikis by testing with a private wiki configuration
  6. 6. Clear any intermediate proxy caches (e.g., Varnish, CDN) that may have cached sensitive content
Caveat Minor version upgrades within the same branch typically have minimal breaking changes; consult the release notes for any notable changes between versions

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-2021-44854 — 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-2021-44854 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