CVE-2023-5546 in Moodle
Summary
by MITRE • 11/09/2023
ID numbers displayed in the quiz grading report required additional sanitizing to prevent a stored XSS risk.
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Analysis
by VulDB Data Team • 09/06/2025
The vulnerability identified as CVE-2023-5546 represents a critical stored cross-site scripting weakness within quiz grading report functionality. This issue arises from insufficient input sanitization when displaying ID numbers in the grading interface, creating a persistent security flaw that can be exploited by malicious actors to inject malicious scripts into the application's user interface. The vulnerability specifically affects systems where quiz grading reports are generated and displayed to users, particularly in educational platforms or learning management systems where such functionality is prevalent.
The technical flaw manifests when ID numbers containing malicious script content are stored within the system and subsequently displayed in the quiz grading report without proper sanitization. This allows attackers to inject javascript code, html tags, or other malicious payloads that persist in the database and execute whenever the grading report is viewed by any user. The vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically classified as a stored XSS attack where the malicious input is stored on the server and then served to other users. The flaw demonstrates poor input validation and output encoding practices that violate fundamental security principles for web application development.
The operational impact of this vulnerability extends beyond simple data corruption, as it can enable attackers to perform various malicious activities including session hijacking, credential theft, redirection to malicious sites, or data exfiltration from the affected system. Users who view the grading reports become victims of the stored XSS attack, potentially leading to unauthorized access to sensitive educational data, student information, or administrative functions within the platform. The persistent nature of stored XSS means that every user who accesses the affected reports remains at risk until the malicious content is removed from the database, making this vulnerability particularly dangerous in environments with multiple administrators or users accessing the same grading interface.
Security mitigations for CVE-2023-5546 should focus on implementing comprehensive input sanitization and output encoding mechanisms throughout the application's data handling pipeline. The most effective approach involves applying proper HTML entity encoding to all user-supplied data before display, ensuring that ID numbers containing special characters are properly escaped to prevent script execution. Additionally, implementing Content Security Policy headers, input validation routines, and regular security audits of data display functions can significantly reduce the risk of similar vulnerabilities. Organizations should also consider implementing automated scanning tools to detect potential XSS vulnerabilities in their web applications and establish secure coding practices that align with OWASP Top Ten recommendations and NIST cybersecurity guidelines. The remediation process should include thorough testing of the patched functionality to ensure that all ID numbers are properly sanitized while maintaining the intended display functionality of the grading reports.