CVE-2025-3643 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in moodle/moodle. A fix is available for moodle/moodle — see the affected versions and patch details below.
Moodle: reflected xss risk in policy tool
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-3643.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
moodle/moodle🐘moodle/moodle🐘moodle/moodle🐘moodle/moodleReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
A flaw was found in Moodle. The return URL in the policy tool required additional sanitizing to prevent a reflected Cross-site scripting (XSS) risk.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | moodle/moodle | all versions | 4.1.18composer require moodle/moodle:^4.1.18 |
| 🐘Packagist | moodle/moodle | ≥ 4.3.0-beta&&< 4.3.12 | 4.3.12composer require moodle/moodle:^4.3.12 |
| 🐘Packagist | moodle/moodle | ≥ 4.4.0-beta&&< 4.4.8 | 4.4.8composer require moodle/moodle:^4.4.8 |
| 🐘Packagist | moodle/moodle | ≥ 4.5.0-beta&&< 4.5.4 | 4.5.4composer require moodle/moodle:^4.5.4 |
Affected Products
moodlemoodleDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for moodle/moodle, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update moodle/moodle to 4.1.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-3643 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2025-3643 in your dependencies?
Find it across Packagist, including transitive dependencies.