CVE-2025-53021
low-risk
Published 2025-06-24
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.
Do I need to act?
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0.29% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
4
CVSS 4.2/10
Medium
NETWORK
/ HIGH complexity
Affected Products (1)
Affected Vendors
References (3)
Third Party Advisory
https://rentry.co/moodle-oauth2-cve
20
/ 100
low-risk
Severity
14/34 · Moderate
Exploitability
1/34 · Minimal
Exposure
5/34 · Minimal