CVE-2015-6733
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 · uneditedGeSHi, as used in the SyntaxHighlight_GeSHi extension and MediaWiki before 1.23.10, 1.24.x before 1.24.3, and 1.25.x before 1.25.2, allows remote attackers to cause a denial of service (resource consumption) via unspecified vectors.
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 confidenceThis is a denial of service vulnerability in the GeSHi (Generic Syntax Highlighter) library as embedded in MediaWiki's SyntaxHighlight_GeSHi extension. Attackers can exploit unspecified vectors to cause excessive resource consumption, likely through malformed or specially crafted code input that triggers inefficient parsing or infinite loops in the syntax highlighting process.
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<= 1.23.9= 1.24.0= 1.24.1= 1.24.2= 1.25.0= 1.25.1CVSS 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
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:N/A:P
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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Identify MediaWiki versionLocate and inspect the version file in your MediaWiki installation. Check includes/DefaultSettings.php or the root-level version file for the $wgVersion variable, or view the page Special:Version on your wiki.Affected if The version is 1.23.9 or lower, 1.24.0, 1.24.1, 1.24.2, 1.25.0, or 1.25.1.
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Verify SyntaxHighlight_GeSHi extension is enabledOpen your LocalSettings.php file in the MediaWiki root directory and search for an include or require statement referencing SyntaxHighlight_GeSHi, such as: wfLoadExtension( 'SyntaxHighlight_GeSHi' ) or require_once extensions/SyntaxHighlight_GeSHi/SyntaxHighlight_GeSHi.php.Affected if The extension is loaded and active.
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Confirm extension is in useCheck if any pages on your wiki use the <syntaxhighlight> or <source> tags, which are provided by this extension. These tags enable syntax highlighting for code blocks.Affected if Users actively employ syntax highlighting tags in wiki content.
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Check GeSHi library version if accessibleIf the GeSHi library is separately installed, inspect the geshi/geshi.php file or the version information within it. The vulnerable library may be embedded within the extension directory at extensions/SyntaxHighlight_GeSHi/geshi/geshi.php.Affected if The embedded GeSHi library version is outdated and affected by this CVE.
Your environment is affected if you run a vulnerable MediaWiki version (1.23.9 or lower, 1.24.0-1.24.2, or 1.25.0-1.25.1) AND have the SyntaxHighlight_GeSHi extension enabled and in use on your wiki.
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.
From vendor dataUpgrade MediaWiki to version 1.23.10, 1.24.3, 1.25.2 or later, or update the SyntaxHighlight_GeSHi extension to its patched version to resolve the resource exhaustion issue.
- Consultation1.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,952.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-6733 — 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-2015-6733 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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- Version or environment caveats, and links to real fixes
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