#VU54985 Stored cross-site scripting in Moodle - CVE-2021-36401

Vulnerability identifier: #VU54985

Vulnerability risk: Medium

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-36401

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Moodle
Web applications / Other software

Vendor: moodle.org

Description

The disclosed vulnerability allows a remote user to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to insufficient sanitization of user-supplied input when exporting to data formats supporting HTML. A remote user can inject and execute arbitrary HTML and script code in user's browser in context of vulnerable website.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Moodle: 3.9.0 - 3.9.7, 3.10.0 - 3.11.0

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External links
https://moodle.org/mod/forum/discuss.php?d=424807
https://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-71981
https://tracker.moodle.org/browse/MDL-71981

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.