CVE-2025-53021 Moodle Session Fixation allows unauthenticated users to hijack sessions via sesskey parameter
Unauthenticated attackers can hijack user sessions via sesskey reuse in Moodle's OAuth2 flow, leading to full account takeover.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2025-53021?
CVE-2025-53021 is a medium-severity authentication bypass vulnerability in Moodle Moodle, published on 24 Jun 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
A session fixation vulnerability in Moodle 3.x through 3.11.18 allows unauthenticated attackers to hijack user sessions via the sesskey parameter. The sesskey can be obtained without authentication and reused within the OAuth2 login flow, resulting in the victim's session being linked to the attacker's. Successful exploitation results in full account takeover. According to the Moodle Releases page, "Bug fixes for security issues in 3.11.x ended 11 December 2023." NOTE: This vulnerability only affects products that are no longer supported by the maintainer.
Weakness: CWE-384
Which versions are affected by CVE-2025-53021?
3 open source packages ship an affected version, including moodle/moodle and moodle. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
moodle/moodle Packagist | From 3.0.0 | 4.0.0 |
moodle/moodle Packagist | From 3.0.0 | 4.0.0 |
moodle Bitnami | From 3.0.0 | 4.1.10 |
Products include Moodle Moodle.
How do I fix CVE-2025-53021?
Upgrade moodle/moodle to 4.0.0 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2025-53021 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-53021 exists.
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-2025-53021, GHSA-cgvv-3455-824j, UBUNTU-CVE-2025-53021.