Vulnerability identifier: #VU49971

Vulnerability risk: Low

CVSSv3.1: 4.7 [CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-20186

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 data in the TeX notation filter. 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: 3.5.0 - 3.5.15, 3.7.0 - 3.7.9, 3.8.0 - 3.8.6, 3.9.0 - 3.9.3, 3.10.0, 3.3 - 3.3.9, 3.6.0 - 3.6.10, 3.1.0 - 3.1.18, 3.4.0 - 3.4.9, 3.2.0 - 3.2.9, 3.0 - 3.0.10

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External links
http://moodle.org/mod/forum/discuss.php?d=417170

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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.