Persistent Cross-Site Scripting in Moodle by Moodle HQ

CVE-2021-27131

Summary

Moodle version 3.10.1 is vulnerable to persistent cross-site scripting due to improper input sanitization in the 'Additional HTML Section' via the 'Header and Footer' parameter in the admin settings. This flaw allows an attacker to potentially execute a stored XSS payload, which could lead to the theft of authentication cookies for both admin and user accounts. Although the vendor argues that inputs can only be supplied by administrators who are expected to use sanitized inputs, the risk associated with allowing unsanitized JavaScript remains a significant concern.

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