CVE-2021-36396: Moodle/moodle Moodle Vulnerable To Server-Side Request Vulnerability

HIGH
Advisory Identifier: GHSA-4rmj-w58m-fvch
Share
CVSS 7.5
CWE-918
Published
Advisory Summary

CVE-2021-36396 is a HIGH (CVSS 7.5) moodle vulnerable to server-side request vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting Moodle/moodle libraries in the Packagist ecosystem. The issue involves moodle vulnerable to server-side request forgery. Remediation is available by upgrading affected packages to version 3.11.1, 3.10.5, 3.9.8.

CVE-2021-36396 at a Glance

CVE Identifier CVE-2021-36396
GHSA Identifier GHSA-4rmj-w58m-fvch
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-918: Server-Side Request Forgery (SSRF)
Affected Product Moodle/moodle
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 7.5

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:H/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 High (I:H)
Availability None (A:N)

How to Fix CVE-2021-36396

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-2021-36396, 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-918: Server-Side Request Forgery (SSRF), where the web server receives a url or similar request from an upstream component and retrieves the contents of this url, but it does not sufficiently ensure that the request is being sent to the expected destination. 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, insufficient redirect handling made it possible to blindly bypass cURL blocked hosts/allowed ports restrictions, resulting in a blind SSRF risk.

CVE-2021-36396 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-2021-36396 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-36396
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=424802

Frequently Asked Questions

What is CVE-2021-36396?
CVE-2021-36396 is a security vulnerability in Moodle/moodle involving Moodle vulnerable to Server-Side Request Forgery under CWE-918: Server-Side Request Forgery (SSRF).
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-2021-36396?
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-2021-36396?
CVE-2021-36396 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.
What CWE is associated with CVE-2021-36396?
CVE-2021-36396 is classified under CWE-918: Server-Side Request Forgery (SSRF) (The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.).
How can I check Packagist dependencies for CVE-2021-36396?
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-4rmj-w58m-fvch",
  "modified" : "2025-03-05T19:05:46Z",
  "published" : "2023-03-06T21:30:18Z",
  "aliases" : [ "CVE-2021-36396" ],
  "summary" : "Moodle vulnerable to Server-Side Request Forgery",
  "details" : "In Moodle, insufficient redirect handling made it possible to blindly bypass cURL blocked hosts/allowed ports restrictions, resulting in a blind SSRF risk.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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-2021-36396"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/moodle/moodle"
  }, {
    "type" : "WEB",
    "url" : "https://moodle.org/mod/forum/discuss.php?d=424802"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-918" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-03-07T20:56:50Z",
    "nvd_published_at" : "2023-03-06T21:15:00Z"
  }
}