CVE-2011-1133
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 · uneditedCross-Site Scripting (XSS) in Xinha, as included in the Serendipity package before 1.5.5, allows remote attackers to execute arbitrary code via plugins/ExtendedFileManager/backend.php.
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 confidenceCross-Site Scripting (XSS) vulnerability in the Xinha WYSIWYG editor's ExtendedFileManager plugin (backend.php) as bundled with Serendipity before version 1.5.5. Remote attackers can inject malicious JavaScript code through unsanitized input, potentially leading to session hijacking or execution of arbitrary code in the context of authenticated users.
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< 1.5.5CVSS 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
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/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 checksWork through these to decide whether this CVE applies to you.
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Locate Serendipity installationIdentify the Serendipity CMS installation directory on your server. Common paths include /var/www/, /home/*/public_html/, or check your web server configuration for the document root.Affected if Serendipity is not installed - not affected by this CVE.
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Determine Serendipity versionOpen the serendipity/serendipity_version.php file in the installation directory, or check the admin dashboard under 'About Serendipity' or 'System Information' for the installed version number.Affected if The installed version is 1.5.5 or later - not affected by this CVE.
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Verify Xinha ExtendedFileManager is presentCheck for the Xinha editor plugin directory within the Serendipity plugins folder. Look for paths like plugins/serendipity_event_xinha/ or include/plugins/xinha/ and confirm the ExtendedFileManager subdirectory and its backend.php file exist.Affected if The Xinha ExtendedFileManager plugin is not present or not in use - likely not affected.
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Inspect backend.php for unsanitized input handlingExamine the ExtendedFileManager/backend.php file in the Xinha plugin directory. Search for code sections that handle user-supplied input (GET/POST parameters) without proper sanitization, particularly before rendering output. Look for missing htmlspecialchars(), htmlentities(), or similar escaping functions around user variables.Affected if The backend.php file contains user input being rendered without sanitization - you are affected by this XSS vulnerability.
You are affected if running Serendipity version below 1.5.5 with the Xinha WYSIWYG editor's ExtendedFileManager plugin enabled and its backend.php processes user input without sanitization.
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 data1.5.5
Upgrade Serendipity to version 1.5.5 or later to include the patched Xinha editor, or if upgrading the entire CMS is not feasible, apply the Xinha patch and validate all user-supplied input in the ExtendedFileManager backend.php is properly sanitized before rendering.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-1133 — 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-2011-1133 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
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