CVE-2021-27131
Moodle 3.10.1 is vulnerable to persistent/stored cross-site scripting (XSS) due to the improper input sanitization on the "Additional HTML Section" via "Header and Footer" parameter in /admin/settings.php.
Does this matter?
Lower severity and a low EPSS score (0.69%). Track it; it rarely justifies an emergency change on its own.
Description
Moodle 3.10.1 is vulnerable to persistent/stored cross-site scripting (XSS) due to the improper input sanitization on the "Additional HTML Section" via "Header and Footer" parameter in /admin/settings.php. This vulnerability is leading an attacker to steal admin and all user account cookies by storing the malicious XSS payload in Header and Footer. NOTE: this is disputed by the vendor because the "Additional HTML Section" for "Header and Footer" can only be supplied by an administrator, who is intentionally allowed to enter unsanitized input (e.g., site-specific JavaScript).
- CVSS 3.1
- 5.4 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
- EPSS
- 0.69% probability · 52th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-79
- Affected
- moodle/moodle
- Source
- cve@mitre.org
EPSS 0.7% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://docs.moodle.org/402/en/Risks
- https://github.com/moodle/moodleProduct
- https://github.com/p4nk4jv/CVEs-Assigned/blob/master/Moodle-3.10.1-CVE-2021-27131.mdExploit
- https://docs.moodle.org/402/en/Risks
- https://github.com/moodle/moodleProduct
- https://github.com/p4nk4jv/CVEs-Assigned/blob/master/Moodle-3.10.1-CVE-2021-27131.mdExploit
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.