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CVE Record

CVE-2020-26121: An issue was discovered in the FileImporter extension for MediaWiki before 1.34.4.

An issue was discovered in the FileImporter extension for MediaWiki before 1.34.4. An attacker can import a file even when the target page is protected against "page creation" and the attacker should not be able to create it. This occurs because of a mishandled distinction between an upload restriction and a create restriction. An attacker cannot leverage this to overwrite anything, but can leverage this to force a wiki to have a page with a disallowed title.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

CVE-2020-26121 is a permission-bypass issue in MediaWiki's FileImporter extension before 1.34.4. A user could import a file even when page-creation protection should block the target title. Sources state this cannot overwrite existing content, but it can create a page with a disallowed title.

Executive priority

Handle through normal patch governance unless the wiki enforces sensitive naming or protected-page controls. Business urgency is lower than code execution or data theft issues, but governance-sensitive wikis should validate quickly.

Technical view

The flaw is a mishandled distinction between upload restrictions and create restrictions in FileImporter. The authorization path could permit importing a file to a protected target that should reject page creation. The public description identifies MediaWiki before 1.34.4 and references Wikimedia task and Gerrit fix material.

Likely exposure

Exposure is likely limited to MediaWiki deployments using the FileImporter extension before 1.34.4. The provided affected-product metadata is incomplete, so package managers and vendor advisories should be checked for exact installed versions.

Exploitation context

The source bundle does not show CISA KEV listing or active exploitation. Public impact is limited to bypassing page-creation protection for imported files; sources explicitly say overwriting is not possible.

Researcher notes

The key security boundary is page creation protection during FileImporter import. Evidence does not include CVSS, CWE, affected CPEs, or exploit reports. Do not assume broader MediaWiki impact beyond FileImporter and the stated pre-1.34.4 condition.

Mitigation direction

  • Upgrade MediaWiki/FileImporter to a vendor-supported version containing the fix, at least 1.34.4 where applicable.
  • Review Fedora advisory updates if using Fedora-packaged MediaWiki components.
  • Check Wikimedia vendor guidance for any deployment-specific FileImporter configuration recommendations.
  • Audit protected-title policies for unexpected pages created through file imports.

Validation and detection

  • Inventory MediaWiki instances and confirm whether FileImporter is installed and enabled.
  • Verify the running MediaWiki/FileImporter version is not before 1.34.4.
  • Review page creation logs for file imports targeting protected or disallowed titles.
  • Confirm protected page-creation controls reject unauthorized file-import targets after remediation.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

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0CVSS vectors
0Timeline events
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5Source links

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Affected products

Products and packages named in the record

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n/an/an/aListed
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