CVE-2021-47857 - CVE House
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Status published Medium CVE-2021-47857

Moodle 3.10.3 - 'label' Persistent Cross Site Scripting

Vulnerability 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.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

  • Vincent666 ibn Winnie

References

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Affected Vendor

Affected Software

Moodle
Vulnerable Versions:
3.10.3

Timeline

Official Publish: January 21st, 2026
Last Modified: March 5th, 2026
Added to House: July 21st, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

Weaknesses (CWE)

CWE-79

MITRE ATT&CK TTPs

T1189 Drive-by Compromise
Initial Access
T1059.007 JavaScript
Execution
T1539 Steal Web Session Cookie
Collection
T1213 Data from Information Repositories
Collection
T1567 Exfiltration Over Web Service
Exfiltration
T1491.001 Defacement
Impact