CVE-2026-26047 is a vulnerability in the Moodle learning management system's TeX formula editor component, specifically when rendering TeX content via the mimetex tool. The issue arises from insufficient enforcement of execution time limits during the processing of TeX formulas. An authenticated user can submit specially crafted TeX expressions that cause mimetex to consume excessive CPU and memory resources, leading to uncontrolled resource consumption. This results in a denial-of-service (DoS) condition, degrading server performance or causing service interruptions. The vulnerability affects Moodle versions 0, 5.0.0, and 5.1.0. The CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) reflects that the attack can be launched remotely over the network, requires low attack complexity, and only requires authenticated privileges but no user interaction. The impact is limited to availability with no confidentiality or integrity compromise. No public exploits have been reported yet, but the vulnerability is published and should be addressed promptly. The root cause is the lack of adequate execution time limits or resource usage restrictions in mimetex when processing complex TeX formulas, which can be exploited to exhaust server resources.

The primary impact of CVE-2026-26047 is denial of service through resource exhaustion. Organizations running affected Moodle versions may experience degraded performance or complete service outages, disrupting e-learning activities. This can affect students, educators, and administrative staff relying on Moodle for course delivery and management. The vulnerability requires authenticated access, so attackers must have valid user credentials, which limits exposure but does not eliminate risk, especially in environments with large user bases or weak credential controls. The disruption can lead to loss of productivity, reputational damage, and potential financial costs related to downtime and incident response. Since Moodle is widely used globally in educational institutions, the scope of impact is significant, particularly in regions with high Moodle adoption. The lack of confidentiality or integrity impact reduces risks related to data breaches but does not diminish the operational consequences of service unavailability.

To mitigate CVE-2026-26047, organizations should first apply any available patches or updates from Moodle that address this vulnerability. If patches are not yet available, administrators should consider disabling the TeX formula editor or the mimetex rendering feature temporarily to prevent exploitation. Implementing strict resource usage limits and execution timeouts at the server or application level for TeX rendering processes can help contain resource consumption. Monitoring server performance and setting alerts for unusual CPU or memory spikes related to mimetex processes can enable early detection of exploitation attempts. Additionally, enforcing strong authentication controls, including multi-factor authentication and regular credential audits, reduces the risk of unauthorized access. Educating users about responsible use of formula editors and monitoring submitted content for suspicious patterns can further reduce risk. Finally, segregating Moodle services on dedicated infrastructure with resource quotas can limit the impact of any exploitation.