CVE-2026-26047: Moodle: moodle: uncontrolled resource consumption in tex formula editor leading to denial of service

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-21 · updated 2026-06-17
Weakness: CWE-400

Description

A denial-of-service vulnerability was identified in Moodle’s TeX formula editor. When rendering TeX content using mimetex, insufficient execution time limits could allow specially crafted formulas to consume excessive server resources. An authenticated user could abuse this behavior to degrade performance or cause service interruption.

Affected products

Moodle: before 4.5.9; from 5.0.0 before 5.0.5; from 5.1.0 before 5.1.2 — fixed in 4.5.9, 5.0.5, 5.1.2

How to fix

Upgrade to a fixed version: Moodle 4.5.9, 5.0.5, 5.1.2. Check the vendor advisory for mitigations.

References

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