CVE-2026-102588 in Moodle
Summary
by MITRE • 09/30/2026
A flaw was found in Moodle. The XML grade import feature lacks proper Cross-Site Request Forgery (CSRF) token validation. By tricking an authenticated user with grade management permissions into visiting a malicious webpage, an attacker can trigger unauthorized requests on the victim's behalf. This flaw allows a remote attacker to set or overwrite student grades without authorization.
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Analysis
by VulDB Data Team • 09/30/2026
The vulnerability identified in Moodle represents a critical failure in access control mechanisms within the platform's XML-based grade import functionality. Specifically, this security defect stems from an absence of proper Cross-Site Request Forgery token validation on endpoints responsible for processing imported grade data. In modern web application architecture, CSRF tokens serve as a cryptographic proof that a request originated from a legitimate user session and was intentionally initiated by that user, rather than being forged by a third party through malicious scripts or links embedded in external sites. The lack of this verification step creates a significant attack surface where authenticated users can be manipulated into performing state-changing actions without their knowledge or consent.
The operational impact of this flaw is severe due to the sensitive nature of grade management permissions within educational institutions. An attacker who successfully exploits this vulnerability does not need to compromise user credentials directly; instead, they rely on social engineering tactics such as tricking a teacher or administrator with appropriate privileges into visiting a malicious webpage containing crafted requests. Once triggered, these forged requests execute against Moodle's backend systems while the victim is still authenticated in their browser session. This allows the remote attacker to arbitrarily set, modify, or overwrite student grades stored within the database. Such unauthorized modifications can lead to significant academic integrity issues, including unfair grading practices, manipulation of final course outcomes, and potential legal or reputational consequences for both students and educational institutions relying on accurate records.
From a technical classification perspective, this vulnerability aligns with CWE-352, which defines Cross-Site Request Forgery as the inclusion of untrusted data in state-changing requests without adequate validation mechanisms. Furthermore, it maps to MITRE ATT&CK technique T1078, specifically relating to valid accounts and potential misuse for privilege escalation or unauthorized access control bypass. The exploitation vector is remote, requiring no prior authentication by the attacker but relying on the victim's existing authenticated session with Moodle. This characteristic makes the vulnerability particularly dangerous in environments where users frequently navigate various web resources while maintaining active sessions with critical administrative tools.
To mitigate this risk, immediate remediation should focus on implementing robust anti-CSRF measures across all grade management endpoints within Moodle. Developers must ensure that every state-changing request includes a unique, unpredictable CSRF token tied to the user's session and validated server-side before processing any data changes. Additionally, enforcing strict SameSite cookie attributes can provide an additional layer of defense by preventing browsers from sending cookies in cross-site requests unless explicitly permitted. Regular security audits focusing on input validation and authentication checks for all administrative functions are essential to prevent similar flaws. Organizations should also consider implementing Content Security Policy headers to restrict the sources from which scripts can be executed, thereby reducing the likelihood of successful exploitation via malicious web pages.