CVE-2025-67857 is a vulnerability identified in Moodle, a widely used open-source learning management system, affecting versions 4.1.0 through 5.1.0. The flaw arises during anonymous assignment submissions where internal user identifiers are inadvertently embedded in URLs sent or displayed to users. This results in unintended exposure of sensitive user information, specifically internal user IDs, which compromises the anonymity intended in these assignment submissions. The vulnerability is classified with a CVSS 3.1 base score of 4.3 (medium severity), reflecting that it impacts confidentiality but not integrity or availability. The attack vector is network-based with low complexity and no privileges required; however, user interaction is necessary as the attacker must access or intercept the URLs containing the sensitive data. Although no known exploits have been reported in the wild, the exposure of internal identifiers could facilitate further targeted attacks or privacy violations. The flaw does not allow unauthorized modification or deletion of data but poses a risk of information disclosure that could violate data protection regulations. The vulnerability was publicly disclosed in early 2026 and is assigned by Fedora’s security team. No official patches or mitigation links were provided at the time of disclosure, indicating that organizations should monitor Moodle updates closely. The issue primarily affects the confidentiality of user data within educational environments relying on Moodle for assignment submissions, particularly where anonymity is a critical feature.

For European organizations, especially educational institutions and universities using Moodle, this vulnerability poses a risk to user privacy and data protection compliance. The inadvertent exposure of internal user IDs during anonymous submissions undermines the anonymity guarantees often required by academic policies and European data protection laws such as the GDPR. This could lead to reputational damage, loss of trust from students and staff, and potential regulatory penalties if personal data is considered exposed. Although the vulnerability does not allow data modification or system disruption, the confidentiality breach could be leveraged for profiling or targeted phishing attacks. The impact is heightened in countries with stringent privacy regulations and active enforcement. Additionally, the exposure could affect collaborative or cross-border educational programs that rely on Moodle, complicating compliance with multiple jurisdictions. The lack of known exploits reduces immediate risk, but the vulnerability should be addressed proactively to prevent future exploitation and maintain compliance.

Organizations should prioritize upgrading Moodle installations to versions beyond 5.1.0 once official patches addressing CVE-2025-67857 are released. Until patches are available, administrators should audit and restrict access to URLs generated during anonymous assignment submissions, ensuring they are not inadvertently shared or logged in publicly accessible locations. Implementing URL tokenization or anonymization techniques to avoid embedding internal user identifiers in URLs can reduce exposure. Monitoring web server logs and network traffic for unusual access patterns to assignment submission URLs may help detect attempted exploitation. Educating users and staff about the sensitivity of assignment submission URLs and discouraging sharing can mitigate risk. Additionally, reviewing Moodle configuration settings related to user anonymity and submission workflows may identify interim controls. Collaboration with Moodle community and security teams to track patch releases and advisories is essential. Finally, documenting the vulnerability and mitigation steps supports compliance audits and incident response readiness.