CVE-2021-40694: Moodle/moodle Moodle Improper Encoding Or Escaping Vulnerability

MODERATE
Advisory Identifier: GHSA-m37g-mwcg-7j7v
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CVSS 4.9
CWE-116
Published
Advisory Summary

CVE-2021-40694 is a MODERATE (CVSS 4.9) moodle improper encoding or escaping vulnerability (CWE-116: Improper Encoding or Escaping of Output) affecting Moodle/moodle libraries in the Packagist ecosystem. The issue involves moodle improper encoding or escaping of output. Remediation is available by upgrading affected packages to version 3.9.10, 3.10.7, 3.11.3.

CVE-2021-40694 at a Glance

CVE Identifier CVE-2021-40694
GHSA Identifier GHSA-m37g-mwcg-7j7v
Severity MODERATE
CVSS v3.1 Base Score 4.9
CWE Classification CWE-116: Improper Encoding or Escaping of Output
Affected Product Moodle/moodle
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 4.9

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:U/C:H/I:N/A:N).

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

How to Fix CVE-2021-40694

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: 3.9.10 
Upgrade moodle/moodle to 3.9.10
moodle/moodle fixed: 3.10.7 
Upgrade moodle/moodle to 3.10.7
moodle/moodle fixed: 3.11.3 
Upgrade moodle/moodle to 3.11.3
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-2021-40694, 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 3.9.10), 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-116: Improper Encoding or Escaping of Output, where the product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. as a result, the intended structure of the message is not preserved. 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

Insufficient escaping of the LaTeX preamble made it possible for site administrators to read files available to the HTTP server system account.

CVE-2021-40694 Affected Moodle/moodle Versions

3 component(s)
Fixed Versions:
3.9.103.10.73.11.3
Product / Package Ecosystem Affected Versions Fixed Version
moodle/moodle
 Packagist
≥ 3.9
< 3.9.10
3.9.10
moodle/moodle
 Packagist
≥ 3.10
< 3.10.7
3.10.7
moodle/moodle
 Packagist
≥ 3.11
< 3.11.3
3.11.3

References

NVD — CVE-2021-40694 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-40694
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2043421
Moodle/moodle Source Repository REPOSITORY
https://github.com/moodle/moodle

Frequently Asked Questions

What is CVE-2021-40694?
CVE-2021-40694 is a security vulnerability in Moodle/moodle involving Moodle Improper Encoding or Escaping of Output under CWE-116: Improper Encoding or Escaping of Output.
Which Moodle/moodle versions are affected?
Affected versions include releases prior to 3.9.10, 3.10.7, 3.11.3 across affected packages: moodle/moodle.
What version fixes CVE-2021-40694?
Upgrading to 3.9.10, 3.10.7, 3.11.3 (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 3.9.10, 3.10.7, 3.11.3. Upgrade your dependency to 3.9.10, 3.10.7, 3.11.3 or later.
What is the CVSS score of CVE-2021-40694?
CVE-2021-40694 has a CVSS v3.1 base score of 4.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2021-40694?
CVE-2021-40694 is classified under CWE-116: Improper Encoding or Escaping of Output (The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.).
How can I check Packagist dependencies for CVE-2021-40694?
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-m37g-mwcg-7j7v",
  "modified" : "2024-04-23T23:37:22Z",
  "published" : "2022-09-30T00:00:29Z",
  "aliases" : [ "CVE-2021-40694" ],
  "summary" : "Moodle Improper Encoding or Escaping of Output",
  "details" : "Insufficient escaping of the LaTeX preamble made it possible for site administrators to read files available to the HTTP server system account.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.9"
      }, {
        "fixed" : "3.9.10"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.10"
      }, {
        "fixed" : "3.10.7"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "moodle/moodle"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.11"
      }, {
        "fixed" : "3.11.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-40694"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2043421"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/moodle/moodle"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-116" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-04-23T23:37:22Z",
    "nvd_published_at" : "2022-09-29T03:15:00Z"
  }
}