Moodle vulnerable to Cross-site Scripting when algebra filter enabled but not functionalGHSA-9f45-9qrw-pp4v
MEDIUMFix: moodle/moodle@9f178c1GHSA-9f45-9qrw-pp4v is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in moodle/moodle. A fix is available for moodle/moodle — see the affected versions and patch details below.
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 GHSA-9f45-9qrw-pp4v.
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
If the algebra filter was enabled but not functional (eg the necessary binaries were missing from the server), it presented an XSS risk.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | moodle/moodle | ≥ 4.1.0&&< 4.1.2 | 4.1.2composer require moodle/moodle:^4.1.2 |
| 🐘Packagist | moodle/moodle | ≥ 4.0.0&&< 4.0.7 | 4.0.7composer require moodle/moodle:^4.0.7 |
| 🐘Packagist | moodle/moodle | ≥ 3.11.0&&< 3.11.13 | 3.11.13composer require moodle/moodle:^3.11.13 |
| 🐘Packagist | moodle/moodle | all versions | 3.9.20composer require moodle/moodle:^3.9.20 |
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 4.1.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9f45-9qrw-pp4v 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 GHSA-9f45-9qrw-pp4v in your dependencies?
Find it across Packagist, including transitive dependencies.