Stored XSS via recursive Mustache helper rendering
Published Sep 30, 2022 · Updated May 20, 2025
XSS in Moodle LMS 4.0 through 4.0.3, 3.11 through 3.11.9, and 3.9 through 3.9.16 allows remote attackers to inject scripts via recursive helpers. The bundled Mustache engine recursively renders helper content containing user input, processing that input again as template content rather than preserving it as inert text. A victim must load the affected rendered content; injected script executes in the Moodle origin, while crafted recursion can instead prevent the page from loading.
Summary
What happened
XSS in Moodle LMS 4.0 through 4.0.3, 3.11 through 3.11.9, and 3.9 through 3.9.16 allows remote attackers to inject scripts via recursive helpers. The bundled Mustache engine recursively renders helper content containing user input, processing that input again as template content rather than preserving it as inert text. A victim must load the affected rendered content; injected script executes in the Moodle origin, while crafted recursion can instead prevent the page from loading.
The record
- CVE
- CVE-2022-40313
- Published
- Sep 30, 2022
- Updated
- May 20, 2025
- Vendor
- Moodle
- Product
- Moodle LMS
- Classifications
- CWE-79, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 30, 2022CVE publishedPublication date reported by the CVE source.
- May 20, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=4.0 to 4.0.3, 3.11 to 3.11.9, 3.9 to 3.9.16 and earlier unsupported versions
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo