Medium severity · published Jun 24, 2025
CVE-2025-53021
A session fixation vulnerability in Moodle 3.x through 3.11.18 allows unauthenticated attackers to hijack user sessions via the sesskey parameter
4.2
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 25% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MO
Moodle · Moodle
3.0.0 through 3.11.18 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-53021
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-53021
Product
https://github.com/moodle/moodle/releases/tag/v3.11.18
Product
https://moodledev.io/general/releases#moodle-311
Third Party Advisory
https://rentry.co/moodle-oauth2-cve
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