7.2

CVE-2021-47857: moodle Cross-site Scripting

CVSS: 7.2v3.1HighAnalyzed
Published 21-01-2026Last modified 05-03-2026
Open JSON

Vulnerability summary

CVE-2021-47857 is a high (CVSS 7.2) Cross-site Scripting vulnerability in moodle. EPSS estimates a 0.38% chance of exploitation in the next 30 days, higher than 30.2% of scored vulnerabilities. 1 public exploit is recorded.

Overall risk
39/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.2/10
010
High · v3.1 (CVE.org)
EPSS score
0.38%
0%100%
Low · +0.01 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1exploit-database

Timeline

  1. 21-01-2026
    PublishedVulnerability first disclosed.
  2. 05-03-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

4 scores · 2 sources · 2 versions

EPSS trend

Probability

0.38%

Chance of exploitation in the next 30 days

Percentile

30%

Versus all other CVEs

30-day change

+0.01 pp

From 0.37% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.38%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

1 found
  • exploit-databasephpUnverified

    Moodle 3.10.3 - 'label' Persistent Cross Site Scripting

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Moodle1 product

1 vendor · 1 product

References

3 links