Vulnerability · Published Jan 21, 2026 · Assigned by VulnCheck
CVE-2021-47857Moodle 3.10.3 - 'label' Persistent Cross Site Scripting
High 7.2
In plain English
A high-severity cross-site scripting in Moodle from Moodle. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities).
Severity (CVSS 3.1)7.2High
Exploit odds (30 days)0.4%top 68.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
Moodle 3.10.3 contains a persistent cross-site scripting vulnerability in the calendar event subtitle field that allows attackers to inject malicious scripts. Attackers can craft a calendar event with malicious JavaScript in the subtitle track label to execute arbitrary code when users view the event.
Affected products (as reported)
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
References
- ExploitDB-49714 exploit
- Official Moodle Project Homepage product
- VulnCheck Advisory: Moodle 3.10.3 - 'label' Persistent Cross Site Scripting third-party-advisory