CVE-2021-36403: Moodle/moodle Moodle Has A Hidden Functionality Vulnerability

MODERATE
Advisory Identifier: GHSA-j9cw-5cpj-9qj5
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CVSS 5.3
CWE-912
Published
Advisory Summary

CVE-2021-36403 is a MODERATE (CVSS 5.3) moodle has a hidden functionality vulnerability (CWE-912: Hidden Functionality) affecting Moodle/moodle libraries in the Packagist ecosystem. The issue involves moodle has a hidden functionality vulnerability. Remediation is available by upgrading affected packages to version 3.11.1, 3.10.5, 3.9.8.

CVE-2021-36403 at a Glance

CVE Identifier CVE-2021-36403
GHSA Identifier GHSA-j9cw-5cpj-9qj5
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-912: Hidden Functionality
Affected Product Moodle/moodle
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 5.3

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

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

How to Fix CVE-2021-36403

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: 3.11.1 
Upgrade moodle/moodle to 3.11.1
moodle/moodle fixed: 3.10.5 
Upgrade moodle/moodle to 3.10.5
moodle/moodle fixed: 3.9.8 
Upgrade moodle/moodle to 3.9.8
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-2021-36403, 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 3.11.1), 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-912: Hidden Functionality, where the product contains functionality that is not documented, not part of the specification, and not accessible through an interface or command sequence that is obvious to the product's users or administrators. 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

In Moodle, in some circumstances, email notifications of messages could have the link back to the original message hidden by HTML, which may pose a phishing risk.

CVE-2021-36403 Affected Moodle/moodle Versions

3 component(s)
Fixed Versions:
3.11.13.10.53.9.8
Product / Package Ecosystem Affected Versions Fixed Version
moodle/moodle
 Packagist
≥ 3.11.0-beta
< 3.11.1
3.11.1
moodle/moodle
 Packagist
≥ 3.10.0-beta
< 3.10.5
3.10.5
moodle/moodle
 Packagist
< 3.9.8
3.9.8

References

NVD — CVE-2021-36403 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-36403
Moodle/moodle Source Repository REPOSITORY
https://github.com/moodle/moodle
moodle.org/mod/forum/discuss.p... WEB
https://moodle.org/mod/forum/discuss.php?d=424809

Frequently Asked Questions

What is CVE-2021-36403?
CVE-2021-36403 is a security vulnerability in Moodle/moodle involving Moodle has a Hidden Functionality vulnerability under CWE-912: Hidden Functionality.
Which Moodle/moodle versions are affected?
Affected versions include releases prior to 3.11.1, 3.10.5, 3.9.8 across affected packages: moodle/moodle.
What version fixes CVE-2021-36403?
Upgrading to 3.11.1, 3.10.5, 3.9.8 (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 3.11.1, 3.10.5, 3.9.8. Upgrade your dependency to 3.11.1, 3.10.5, 3.9.8 or later.
What is the CVSS score of CVE-2021-36403?
CVE-2021-36403 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2021-36403?
CVE-2021-36403 is classified under CWE-912: Hidden Functionality (The product contains functionality that is not documented, not part of the specification, and not accessible through an interface or command sequence that is obvious to the product's users or administrators.).
How can I check Packagist dependencies for CVE-2021-36403?
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-j9cw-5cpj-9qj5",
  "modified" : "2023-03-13T22:06:44Z",
  "published" : "2023-03-07T00:30:25Z",
  "aliases" : [ "CVE-2021-36403" ],
  "summary" : "Moodle has a Hidden Functionality vulnerability",
  "details" : "In Moodle, in some circumstances, email notifications of messages could have the link back to the original message hidden by HTML, which may pose a phishing risk.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.11.0-beta"
      }, {
        "fixed" : "3.11.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.10.0-beta"
      }, {
        "fixed" : "3.10.5"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.9.8"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-36403"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/moodle/moodle"
  }, {
    "type" : "WEB",
    "url" : "https://moodle.org/mod/forum/discuss.php?d=424809"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-912" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-03-08T00:16:56Z",
    "nvd_published_at" : "2023-03-06T23:15:00Z"
  }
}