CVE-2025-67850: Moodle: moodle: cross-site scripting vulnerability via inadequate input filtering in formula editor

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-03 · updated 2026-06-17
Weakness: CWE-79

Description

A flaw was found in moodle. This vulnerability, known as Cross-Site Scripting (XSS), occurs due to insufficient checks on user-provided data in the formula editor's arithmetic expression fields. A remote attacker could inject malicious code into these fields. When other users view these expressions, the malicious code would execute in their web browsers, potentially compromising their data or leading to unauthorized actions.

Affected products

Moodle: before 4.1.22; from 4.4.0 before 4.4.11; from 4.5.0 before 4.5.8; from 5.0.0 before 5.0.4; 5.1.0 — fixed in 4.1.22, 4.4.11, 4.5.8, 5.0.4

How to fix

Upgrade to a fixed version: Moodle 4.1.22, 4.4.11, 4.5.8, 5.0.4. Check the vendor advisory for mitigations.

References

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