CVE-2025-67857 is a vulnerability identified in multiple recent versions of Moodle, a widely used open-source learning management system. The flaw arises during the process of anonymous assignment submissions, where internal user identifiers, such as user IDs, are inadvertently included in URLs sent or displayed. This results in unintended data exposure, as these URLs can be viewed by unauthorized parties, thereby compromising the anonymity that Moodle aims to provide in such submission scenarios. The vulnerability does not allow attackers to alter data or disrupt service availability but does leak sensitive information that could be used for further reconnaissance or targeted attacks. The issue requires no authentication privileges to exploit but does require user interaction to access the affected URLs. The vulnerability has been assigned a CVSS 3.1 score of 4.3, indicating a medium severity level, primarily due to its impact on confidentiality without affecting integrity or availability. No public exploits have been reported to date, but the exposure of internal user IDs could have privacy implications, especially in educational environments where anonymity is critical. The affected versions include Moodle 4.1.0, 4.4.0, 4.5.0, 5.0.0, and 5.1.0. The flaw was published in early 2026, and no official patches or mitigation links were provided in the source data, suggesting that organizations should monitor Moodle advisories closely for updates.

The primary impact of CVE-2025-67857 is the compromise of user anonymity and confidentiality within Moodle environments. Exposure of internal user identifiers can lead to privacy violations, undermining trust in the platform, especially in academic settings where anonymous submissions are critical for unbiased grading and feedback. Attackers or unauthorized viewers could use the exposed IDs to correlate user activity, potentially facilitating targeted phishing, social engineering, or further exploitation. Although the vulnerability does not allow data modification or service disruption, the confidentiality breach could have legal and reputational consequences for educational institutions and organizations relying on Moodle. The scope of impact is significant given Moodle's global adoption in schools, universities, and government agencies. The ease of exploitation (no privileges required) increases risk, though user interaction is necessary. The absence of known exploits reduces immediate threat but does not eliminate future risk.

Organizations should immediately review their Moodle deployment versions and plan upgrades to patched releases once available. Until official patches are released, administrators can implement URL filtering or proxy rules to block or sanitize URLs containing user identifiers during anonymous submissions. Configuring Moodle to minimize or disable anonymous submission features temporarily can reduce exposure. Monitoring web server logs for suspicious access patterns to URLs containing user IDs can help detect exploitation attempts. Educating users about the risks of sharing URLs and enforcing strict access controls on submission pages can further mitigate risk. Collaboration with Moodle community forums and security advisories is essential to stay informed about patches or workarounds. Additionally, organizations should conduct privacy impact assessments to understand the implications of this data exposure and adjust policies accordingly.