CVE-2021-36394: moodle Session Fixation
CVSS: 9.8v3.1CriticalModified
AliasesUBUNTU-CVE-2021-36394
Published 06-03-2023Last modified 06-03-2025
Vulnerability summary
CVE-2021-36394 is a critical (CVSS 9.8) Session Fixation vulnerability in moodle. EPSS estimates a 7.03% chance of exploitation in the next 30 days, higher than 94.1% of scored vulnerabilities.
CVSS score
9.8/10
010
Critical · v3.1 (NVD)EPSS score
7.03%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Timeline
- 06-03-2023PublishedVulnerability first disclosed.
- 06-03-2025Last modifiedVulnerability information updated.
Description
In Moodle, a remote code execution risk was identified in the Shibboleth authentication plugin.
CVSS metrics
2 scores · 2 sources · 1 versionCritical 9.8Preferred score · NVD (NIST)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSourcesAll 2 agree
- OSV · UbuntuEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
7.03%
Chance of exploitation in the next 30 days
Percentile
94%
Versus all other CVEs
30-day change
0.00 pp
From 7.03% on 21-09-2026
21-09-202621-10-2026
EPSS score7.03%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-384Session FixationAuthenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.
- CWE-94Improper Control of Generation of Code ('Code Injection')The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
Affected systems
Moodle1 product
- moodle< 3.9.8 | ≥ 3.10.0, < 3.10.5 | ≥ 3.11.0, < 3.11.1
Ubuntu1 product
- moodleAll versions (No fix recorded)
2 vendors · 2 products