MoodleCMS
CVE-2025-3643
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 · uneditedA flaw was found in Moodle. The return URL in the policy tool required additional sanitizing to prevent a reflected Cross-site scripting (XSS) risk.
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 confidenceA reflected Cross-site scripting (XSS) vulnerability exists in Moodle's policy tool. The return URL parameter is not properly sanitized before being reflected in the HTTP response, allowing an attacker to inject malicious HTML/JavaScript that executes in the victim's browser when they interact with the crafted URL.
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
< 4.1.18>= 4.3.0, < 4.3.12>= 4.4.0, < 4.4.8>= 4.5.0, < 4.5.4CVSS 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
- Low
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/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.
-
Check installed Moodle versionOpen the version.php file in the Moodle root directory and read the $version variable value, or go to Site Administration > Server > Environment to view the displayed Moodle version numberAffected if The installed version is less than 4.1.18, OR between 4.3.0 and 4.3.11 inclusive, OR between 4.4.0 and 4.4.7 inclusive, OR between 4.5.0 and 4.5.3 inclusive
-
Verify policy tool is enabledNavigate to Site Administration > Users > Privacy and policies > Policies and procedures to confirm the policy tool is active, or check the plugins management page for policy tool statusAffected if The policy tool plugin is installed and enabled on the site
-
Identify policy tool endpoints handling return URLExamine the Moodle source code in the policy tool directory (typically /policy/) for files that handle the return or returnurl HTTP parameter, looking for places where this parameter is output without HTML escapingAffected if The policy tool code reflects the return URL parameter directly into HTML output without sanitization
You are affected if your Moodle version falls within one of the vulnerable ranges AND the policy tool is enabled, as the unsanitized return URL parameter can be exploited for reflected XSS.
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 · scoped4.1.184.3.124.4.8
Implement proper output encoding/sanitization of the return URL parameter in the policy tool to prevent XSS. This typically involves HTML-escaping the URL value before rendering it in any HTML context.
Moodle 4.1.18 / 4.3.12 / 4.4.8 / 4.5.4 (depending on your current branch)
- Upgrade to Moodle 4.1.18 or later if running a 4.1.x version
- Upgrade to Moodle 4.3.12 or later if running a 4.3.x version
- Upgrade to Moodle 4.4.8 or later if running a 4.4.x version
- Upgrade to Moodle 4.5.4 or later if running a 4.5.x version
- After upgrading, verify the policy tool functionality works correctly and the return URL is properly sanitized
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Moodle
Scoped from the published advisory
- Consultation2.0 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 $1,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-3643 — 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-2025-3643 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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