CVE-2025-53021: Moodle/moodle Moodle Session Fixation Allows Unauthenticated Vulnerability

MODERATE
Advisory Identifier: GHSA-cgvv-3455-824j
Share
CVSS 4.2
CWE-384
Published
Advisory Summary

CVE-2025-53021 is a MODERATE (CVSS 4.2) moodle session fixation allows unauthenticated vulnerability (CWE-384: Session Fixation) affecting Moodle/moodle libraries in the Packagist ecosystem. The issue involves moodle session fixation allows unauthenticated users to hijack sessions via sesskey parameter. Remediation is available by upgrading affected packages to version 4.0.0.

CVE-2025-53021 at a Glance

CVE Identifier CVE-2025-53021
GHSA Identifier GHSA-cgvv-3455-824j
Severity MODERATE
CVSS v3.1 Base Score 4.2
CWE Classification CWE-384: Session Fixation
Affected Product Moodle/moodle
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 4.2

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2025-53021

To remediate this vulnerability, upgrade all affected Moodle/moodle dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

moodle/moodle fixed: 4.0.0 
Upgrade moodle/moodle to 4.0.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for moodle/moodle

How to Check if You Are Affected

To determine whether your application is affected by CVE-2025-53021, inspect your project dependencies for Moodle/moodle:

inspect dependencies for moodle/moodle

Analyze the terminal output to locate any version of Moodle/moodle in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.0.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-384: Session Fixation, where authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions. In Moodle/moodle, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2025-53021 Affected Moodle/moodle Versions

1 component(s)
Fixed Versions:
4.0.0
Product / Package Ecosystem Affected Versions Fixed Version
moodle/moodle
 Packagist
≥ 3.0.0
< 4.0.0
4.0.0

References

NVD — CVE-2025-53021 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-53021
Moodle/moodle Source Repository REPOSITORY
https://github.com/moodle/moodle
Moodle/moodle Release RELEASE
https://github.com/moodle/moodle/releases/tag/v3.11.18
moodledev.io/general/releases WEB
https://moodledev.io/general/releases#moodle-311
rentry.co/moodle-oauth2-cve WEB
https://rentry.co/moodle-oauth2-cve

Frequently Asked Questions

What is CVE-2025-53021?
CVE-2025-53021 is a security vulnerability in Moodle/moodle involving Moodle Session Fixation allows unauthenticated users to hijack sessions via sesskey parameter under CWE-384: Session Fixation.
Which Moodle/moodle versions are affected?
Affected versions include releases prior to 4.0.0 across affected packages: moodle/moodle.
What version fixes CVE-2025-53021?
Upgrading to 4.0.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is moodle/moodle affected?
Yes, moodle/moodle is affected in releases prior to 4.0.0. Upgrade your dependency to 4.0.0 or later.
What is the CVSS score of CVE-2025-53021?
CVE-2025-53021 has a CVSS v3.1 base score of 4.2 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2025-53021?
CVE-2025-53021 is classified under CWE-384: Session Fixation (Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.).
How can I check Packagist dependencies for CVE-2025-53021?
Run the dependency tree command: 'inspect dependencies for moodle/moodle'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-cgvv-3455-824j",
  "modified" : "2025-06-26T14:12:34Z",
  "published" : "2025-06-24T21:30:29Z",
  "aliases" : [ "CVE-2025-53021" ],
  "summary" : "Moodle Session Fixation allows unauthenticated users to hijack sessions via sesskey parameter",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.0.0"
      }, {
        "fixed" : "4.0.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 3.11.18"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-53021"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/moodle/moodle"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/moodle/moodle/releases/tag/v3.11.18"
  }, {
    "type" : "WEB",
    "url" : "https://moodledev.io/general/releases#moodle-311"
  }, {
    "type" : "WEB",
    "url" : "https://rentry.co/moodle-oauth2-cve"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-384" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-06-26T14:12:34Z",
    "nvd_published_at" : "2025-06-24T20:15:26Z"
  }
}