CVE-2021-20184: Moodle/moodle Moodle Grade Information Disclosure Vulnerability

MODERATE
Advisory Identifier: GHSA-mm73-86f9-5x5c
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CVSS 4.3
CWE-354
Published
Advisory Summary

CVE-2021-20184 is a MODERATE (CVSS 4.3) moodle grade information disclosure vulnerability (CWE-354: Improper Validation of Integrity Check Value) affecting Moodle/moodle libraries in the Packagist ecosystem. The issue involves moodle grade information disclosure in grade's external fetch functions. Remediation is available by upgrading affected packages to version 3.8.7, 3.9.4, 3.10.1.

CVE-2021-20184 at a Glance

CVE Identifier CVE-2021-20184
GHSA Identifier GHSA-mm73-86f9-5x5c
Severity MODERATE
CVSS v3.1 Base Score 4.3
CWE Classification CWE-354: Improper Validation of Integrity Check Value
Affected Product Moodle/moodle
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 4.3

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

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

How to Fix CVE-2021-20184

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: 3.8.7 
Upgrade moodle/moodle to 3.8.7
moodle/moodle fixed: 3.9.4 
Upgrade moodle/moodle to 3.9.4
moodle/moodle fixed: 3.10.1 
Upgrade moodle/moodle to 3.10.1
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-2021-20184, 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 3.8.7), 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-354: Improper Validation of Integrity Check Value, where the product does not validate or incorrectly validates the integrity check values or "checksums" of a message. this may prevent it from detecting if the data has been modified or corrupted in transmission. 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

It was found in Moodle before version 3.10.1, 3.9.4 and 3.8.7 that a insufficient capability checks in some grade related web services meant students were able to view other students grades.

CVE-2021-20184 Affected Moodle/moodle Versions

3 component(s)
Fixed Versions:
3.8.73.9.43.10.1
Product / Package Ecosystem Affected Versions Fixed Version
moodle/moodle
 Packagist
≥ 3.8
< 3.8.7
3.8.7
moodle/moodle
 Packagist
≥ 3.9
< 3.9.4
3.9.4
moodle/moodle
 Packagist
≥ 3.10
< 3.10.1
3.10.1

References

NVD — CVE-2021-20184 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-20184
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=417167

Frequently Asked Questions

What is CVE-2021-20184?
CVE-2021-20184 is a security vulnerability in Moodle/moodle involving Moodle Grade information disclosure in grade's external fetch functions under CWE-354: Improper Validation of Integrity Check Value.
Which Moodle/moodle versions are affected?
Affected versions include releases prior to 3.8.7, 3.9.4, 3.10.1 across affected packages: moodle/moodle.
What version fixes CVE-2021-20184?
Upgrading to 3.8.7, 3.9.4, 3.10.1 (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 3.8.7, 3.9.4, 3.10.1. Upgrade your dependency to 3.8.7, 3.9.4, 3.10.1 or later.
What is the CVSS score of CVE-2021-20184?
CVE-2021-20184 has a CVSS v3.1 base score of 4.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2021-20184?
CVE-2021-20184 is classified under CWE-354: Improper Validation of Integrity Check Value (The product does not validate or incorrectly validates the integrity check values or "checksums" of a message. This may prevent it from detecting if the data has been modified or corrupted in transmission.).
How can I check Packagist dependencies for CVE-2021-20184?
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-mm73-86f9-5x5c",
  "modified" : "2024-04-23T23:37:58Z",
  "published" : "2022-05-24T17:40:31Z",
  "aliases" : [ "CVE-2021-20184" ],
  "summary" : "Moodle Grade information disclosure in grade's external fetch functions",
  "details" : "It was found in Moodle before version 3.10.1, 3.9.4 and 3.8.7 that a insufficient capability checks in some grade related web services meant students were able to view other students grades.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.8"
      }, {
        "fixed" : "3.8.7"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.9"
      }, {
        "fixed" : "3.9.4"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.10"
      }, {
        "fixed" : "3.10.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-20184"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/moodle/moodle"
  }, {
    "type" : "WEB",
    "url" : "https://moodle.org/mod/forum/discuss.php?d=417167"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-354" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-04-23T23:37:58Z",
    "nvd_published_at" : "2021-01-28T19:15:00Z"
  }
}