CVE-2021-27131 Moodle vulnerable to stored Cross-site Scripting
Stored XSS in Moodle allows attackers to steal admin and user cookies via the Header and Footer settings, though the vendor disputes this as intended admin functionality.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2021-27131?
CVE-2021-27131 is a medium-severity cross-site scripting vulnerability in Moodle Moodle, published on 16 May 2023. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official 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).
Weakness: CWE-79
Which versions are affected by CVE-2021-27131?
3 open source packages ship an affected version, including moodle/moodle and moodle. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
moodle/moodle Packagist | All versions to 3.10.1 | None |
moodle/moodle Packagist | All versions to 3.10.1 | None |
moodle Bitnami | From 3.10.1 | 3.10.2 |
Products include Moodle Moodle.
How do I fix CVE-2021-27131?
Apply the vendor's patch.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2021-27131 being exploited?
There is no known exploitation of CVE-2021-27131 in the wild and no public exploit code.
Other vulnerabilities in Moodle Moodle
- CVE-2006-4935 File upload in n/a
- CVE-2006-4936 Moodle does not properly validate module instance id
- CVE-2004-2233 Unknown "front page vulnerability with Moodle servers" for Moodle before 1.3.2 has unknown impact and attack vectors.
- CVE-2004-2235 Cross-site scripting in n/a
- CVE-2004-2236 Other in n/a
Sources
Also known as BIT-moodle-2021-27131, GHSA-w2pm-fr62-jgv4.