CVE-2021-21809: Moodle/moodle Moodle Command Execution Vulnerability Exists Vulnerability

CRITICAL
Advisory Identifier: GHSA-c7jj-vfmr-j9mj
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CVSS 9.1
CWE-732
Published
Advisory Summary

CVE-2021-21809 is a CRITICAL (CVSS 9.1) moodle command execution vulnerability exists vulnerability (CWE-732: Incorrect Permission Assignment for Critical Resource) affecting Moodle/moodle libraries in the Packagist ecosystem. The issue involves moodle command execution vulnerability exists in the default legacy spellchecker plugin. Remediation is available in the latest vendor maintenance releases.

CVE-2021-21809 at a Glance

CVE Identifier CVE-2021-21809
GHSA Identifier GHSA-c7jj-vfmr-j9mj
Severity CRITICAL
CVSS v3.1 Base Score 9.1
CWE Classification CWE-732: Incorrect Permission Assignment for Critical Resource
Affected Product Moodle/moodle
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 9.1

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

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

How to Fix CVE-2021-21809

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: Latest secure release 
Upgrade moodle/moodle to Latest secure release
moodle/moodle fixed: Latest secure release 
Upgrade moodle/moodle to Latest secure release
moodle/moodle fixed: Latest secure release 
Upgrade moodle/moodle to Latest secure release
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-2021-21809, 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 the patched release), 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-732: Incorrect Permission Assignment for Critical Resource, where the product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors. 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 command execution vulnerability exists in the default legacy spellchecker plugin in a few Moodle multiple specific versions. A specially crafted series of HTTP requests can lead to command execution. An attacker must have administrator privileges to exploit this vulnerabilities.

CVE-2021-21809 Affected Moodle/moodle Versions

3 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
moodle/moodle
 Packagist
3.10.0
All 1 versions
3.10.0
None specified
moodle/moodle
 Packagist
3.11.2
All 1 versions
3.11.2
None specified
moodle/moodle
 Packagist
3.8.0
All 1 versions
3.8.0
None specified

References

NVD — CVE-2021-21809 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-21809
Moodle/moodle Source Repository REPOSITORY
https://github.com/moodle/moodle
talosintelligence.com/vulnerability_repor... WEB
https://talosintelligence.com/vulnerability_reports/TALOS-2021-1277
Moodle/moodle Security Information SECURITY
http://packetstormsecurity.com/files/164481/Moodle-SpellChecker-Path-Authenticated-Remote-Command-Execution.html

Frequently Asked Questions

What is CVE-2021-21809?
CVE-2021-21809 is a security vulnerability in Moodle/moodle involving Moodle command execution vulnerability exists in the default legacy spellchecker plugin under CWE-732: Incorrect Permission Assignment for Critical Resource.
Which Moodle/moodle versions are affected?
Affected versions include releases prior to current release patches across affected packages: moodle/moodle.
What version fixes CVE-2021-21809?
Upgrading to current release patches (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 Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2021-21809?
CVE-2021-21809 has a CVSS v3.1 base score of 9.1 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H.
What CWE is associated with CVE-2021-21809?
CVE-2021-21809 is classified under CWE-732: Incorrect Permission Assignment for Critical Resource (The product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.).
How can I check Packagist dependencies for CVE-2021-21809?
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-c7jj-vfmr-j9mj",
  "modified" : "2024-04-24T17:29:50Z",
  "published" : "2022-05-24T19:06:04Z",
  "aliases" : [ "CVE-2021-21809" ],
  "summary" : "Moodle command execution vulnerability exists in the default legacy spellchecker plugin",
  "details" : "A command execution vulnerability exists in the default legacy spellchecker plugin in a few Moodle multiple specific versions. A specially crafted series of HTTP requests can lead to command execution. An attacker must have administrator privileges to exploit this vulnerabilities.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "versions" : [ "3.10.0" ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "versions" : [ "3.11.2" ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "versions" : [ "3.8.0" ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-21809"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/moodle/moodle"
  }, {
    "type" : "WEB",
    "url" : "https://talosintelligence.com/vulnerability_reports/TALOS-2021-1277"
  }, {
    "type" : "WEB",
    "url" : "http://packetstormsecurity.com/files/164481/Moodle-SpellChecker-Path-Authenticated-Remote-Command-Execution.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-732" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-04-24T17:29:50Z",
    "nvd_published_at" : "2021-06-23T22:15:00Z"
  }
}