CVE-2020-15164
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 · uneditedin Scratch Login (MediaWiki extension) before version 1.1, any account can be logged into by using the same username with leading, trailing, or repeated underscore(s), since those are treated as whitespace and trimmed by MediaWiki. This affects all users on any wiki using this extension. Since version 1.1, comments by users whose usernames would be trimmed on MediaWiki are ignored when searching for the verification code.
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 confidenceThe Scratch Login MediaWiki extension before v1.1 suffers from an authentication bypass where an attacker can log into any user account by using the target username with leading, trailing, or repeated underscore characters. MediaWiki's string trimming treats these variations as equivalent to the legitimate username, allowing unauthorized access to any account on affected wikis.
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< 1.1CVSS 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
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/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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Confirm Scratch Login extension is installedCheck the MediaWiki extensions directory for the Scratch Login extension, typically in /path/to/mediawiki/extensions/ScratchLogin/, or query the database table 'extension' or 'actor' tables if available.Affected if The ScratchLogin directory or extension record exists in the MediaWiki installation.
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Determine installed Scratch Login versionLocate the version file or check the extension's PHP files for the version number, typically found in the extension.json or the main extension file like ScratchLogin.php.Affected if The version is below 1.1 (e.g., 1.0, 0.x, or no version indicated).
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Verify authentication uses Scratch LoginCheck MediaWiki's LocalSettings.php for the line 'wfLoadExtension( "ScratchLogin" )' or similar require/include statements that load the extension.Affected if Scratch Login is loaded and used for authentication on the wiki.
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Check MediaWiki username trimming behaviorTest by attempting to create or authenticate with a username containing leading underscores (e.g., '_admin'), trailing underscores ('admin_'), or repeated underscores ('a__dmin') and observe if MediaWiki treats these as equivalent to the base username.Affected if Usernames with underscore variations are accepted or treated as equivalent to existing accounts.
A user is affected if the Scratch Login extension is installed with a version below 1.1 and authentication relies on this extension, allowing usernames with leading, trailing, or repeated underscores to bypass authentication for existing accounts.
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 · scoped1.1
Upgrade to Scratch Login version 1.1 or later, which addresses the username trimming issue. Additionally, implement strict username validation at login to reject usernames that would be trimmed by MediaWiki.
1.1
- Identify the currently installed version of the Scratch Login MediaWiki extension
- Download Scratch Login version 1.1 or later from the extension repository
- Replace the existing mediawiki-scratch-login extension files with the new version
- Run any necessary database updates or maintenance scripts for the extension
- Clear any caches to ensure the new code is loaded
- Verify that username trimming no longer allows authentication bypass by testing with modified usernames
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 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 $3,648.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-15164 — 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-2020-15164 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
- No spam, self-promotion, credentials, or personal data