Account takeover via reusable OAuth2 sesskey
Published Jun 24, 2025 · Updated Jun 24, 2025
Session fixation in Moodle LMS 3.0.0 through 3.11.18 allows remote attackers to hijack accounts through the OAuth2 login flow. The login page exposes an unauthenticated sesskey that auth/oauth2/login.php accepts in a crafted OAuth2 URL, binding the victim's completed login to the attacker's pre-created session. Exploitation requires a victim to follow the crafted OAuth2 login URL and authenticate; success gives the attacker control of that victim's Moodle account.
Summary
What happened
Session fixation in Moodle LMS 3.0.0 through 3.11.18 allows remote attackers to hijack accounts through the OAuth2 login flow. The login page exposes an unauthenticated sesskey that auth/oauth2/login.php accepts in a crafted OAuth2 URL, binding the victim's completed login to the attacker's pre-created session. Exploitation requires a victim to follow the crafted OAuth2 login URL and authenticate; success gives the attacker control of that victim's Moodle account.
The record
- CVE
- CVE-2025-53021
- Published
- Jun 24, 2025
- Updated
- Jun 24, 2025
- Vendor
- Moodle
- Product
- Moodle LMS
- Classifications
- CWE-384, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 24, 2025CVE publishedPublication date reported by the CVE source.
- Jun 24, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=3 <=3.11.18
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Moodle OAuth2 Session Fixation PoCproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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