MoodleCMS
CVE-2011-4294
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 · uneditedThe error-message functionality in Moodle 1.9.x before 1.9.13, 2.0.x before 2.0.4, and 2.1.x before 2.1.1 does not ensure that a continuation link refers to an http or https URL for the local Moodle instance, which might allow attackers to trick users into visiting arbitrary web sites 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 · high confidenceMoodle's error-message functionality fails to validate that continuation links point to legitimate local http or https URLs, allowing attackers to craft malicious links that redirect users to external websites. This is an open redirect vulnerability in the error handling code affecting versions 1.9.x before 1.9.13, 2.0.x before 2.0.4, and 2.1.x before 2.1.1.
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
MoodleCMS
= 1.9.1= 1.9.2= 1.9.3= 1.9.4= 1.9.5= 1.9.6= 1.9.7= 1.9.8= 1.9.9= 1.9.10= 1.9.11= 1.9.12CVSS 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
- M
- Authentication
- None
- Confidentiality
- None
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:M/Au:N/C:N/I:P/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 Moodle versionAccess the admin panel and locate the version information, typically found at /admin/ or in the version.php file within the Moodle installation directoryAffected if The installed version is 1.9.1 through 1.9.12, 2.0.x through 2.0.3, or 2.1.x through 2.1.0 (versions before 1.9.13, 2.0.4, or 2.1.1)
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Locate error message handling codeSearch the codebase for files handling error messages and redirection logic, particularly functions that generate continuation or return links displayed to users after an errorAffected if The error handling code processes a 'return' or 'continuation' parameter without strict URL validation
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Inspect URL validation in error handlersExamine the error handling code to verify whether continuation links are validated to ensure they point only to local http or https URLs within the same domainAffected if No validation exists, or validation only checks for 'http' or 'https' prefix without verifying the URL remains on the local domain
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Test redirection behaviorIf you have a test environment, trigger an error message and provide a crafted continuation parameter with an external URL (such as ?return=http://attacker.com) to observe whether the application redirects to the external siteAffected if The application redirects to the external URL provided in the continuation parameter rather than rejecting or stripping it
You are affected if your Moodle version falls within 1.9.1-1.9.12, 2.0.x-2.0.3, or 2.1.x-2.1.0 AND the error handling code lacks proper validation ensuring continuation links remain on local URLs.
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 dataImplement strict URL validation for continuation links in error messages, ensuring they only point to local Moodle URLs (relative paths or absolute http/https URLs within the same domain).
Fix this in Moodle
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 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 $1,664.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-4294 — 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-2011-4294 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
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