Home/CVE/Moodle 3.10.3 contains a persistent cross-site scripting vulnerability in the calendar event subtitle field that allows
CVE

CVE-2021-47857

Moodle 3.10.3 contains a persistent cross-site scripting vulnerability in the calendar event subtitle field that allows

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.

HIGH · CVSS 7.2 EPSS 0.0005
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  • Public exploit or PoC is available
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
▤

Affected Products & Versions

1
moodleall versions
⚠

Public Exploits & PoCs

1
pocwww.exploit-db.com · 49714www.exploit-db.com
▣

Scoring & Timeline

7.2
HIGH · CVSS v3.1 · disclosure@vulncheck.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD21 Jan 2026 · 06:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
SSVC triage · cisa-vulnrichment
Exploitation
poc
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
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References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://moodle.org/Product
https://www.vulncheck.com/advisories/moodle-label-persistent-cross-site-scriptingThird Party Advisory
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