CVE-2021-36440: Showdoc/showdoc Unrestricted File Upload Vulnerability

Q: What is CVE-2021-36440?

CVE-2021-36440 is a security vulnerability in Showdoc/showdoc involving Unrestricted File Upload in ShowDoc v2.9.5 under CWE-434: Unrestricted Upload of File with Dangerous Type.

Q: Which Showdoc/showdoc versions are affected?

Affected versions include releases prior to 2.9.6 across affected packages: showdoc/showdoc.

Q: What version fixes CVE-2021-36440?

Upgrading to 2.9.6 (or the latest patched release for your respective branch) resolves the vulnerability.

Q: Is showdoc/showdoc affected?

Yes, showdoc/showdoc is affected in releases prior to 2.9.6. Upgrade your dependency to 2.9.6 or later.

Q: What is the CVSS score of CVE-2021-36440?

CVE-2021-36440 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Q: What CWE is associated with CVE-2021-36440?

CVE-2021-36440 is classified under CWE-434: Unrestricted Upload of File with Dangerous Type (The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.).

Q: How can I check Packagist dependencies for CVE-2021-36440?

Run the dependency tree command: 'inspect dependencies for showdoc/showdoc'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.

CRITICAL

Advisory Identifier: GHSA-c442-3278-rhrg

CVSS 9.8

CWE-434

Published 2021-09-09

Advisory Summary

CVE-2021-36440 is a CRITICAL (CVSS 9.8) unrestricted file upload vulnerability (CWE-434: Unrestricted Upload of File with Dangerous Type) affecting Showdoc/showdoc libraries in the Packagist ecosystem. The issue involves unrestricted file upload in showdoc v2.9.5. Remediation is available by upgrading affected packages to version 2.9.6.

CVE-2021-36440 at a Glance

CVE Identifier CVE-2021-36440

GHSA Identifier GHSA-c442-3278-rhrg

Severity CRITICAL

CVSS v3.1 Base Score 9.8

CWE Classification CWE-434: Unrestricted Upload of File with Dangerous Type

Affected Product Showdoc/showdoc

Package Ecosystem Packagist

Published Date 2021-09-09

Last Updated 2021-09-16

Security Impact

CVSS: 9.8

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:H/I:H/A:H).

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 High (C:H)

Integrity High (I:H)

Availability High (A:H)

How to Fix CVE-2021-36440

To remediate this vulnerability, upgrade all affected Showdoc/showdoc dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

showdoc/showdoc fixed: 2.9.6

Upgrade showdoc/showdoc to 2.9.6

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 showdoc/showdoc

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-36440, inspect your project dependencies for Showdoc/showdoc:

inspect dependencies for showdoc/showdoc

Analyze the terminal output to locate any version of Showdoc/showdoc in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.9.6), 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-434: Unrestricted Upload of File with Dangerous Type, where the product allows the upload or transfer of dangerous file types that are automatically processed within its environment. In Showdoc/showdoc, 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

Unrestricted File Upload in ShowDoc v2.9.5 allows remote attackers to execute arbitrary code via the 'file_url' parameter in the component AdminUpdateController.class.php'.

CVE-2021-36440 Affected Showdoc/showdoc Versions

1 component(s)

Fixed Versions:

2.9.6

Product / Package	Ecosystem	Affected Versions	Fixed Version
showdoc/showdoc	Packagist	< 2.9.6	2.9.6

References

NVD — CVE-2021-36440 NVD

https://nvd.nist.gov/vuln/detail/CVE-2021-36440

Showdoc/showdoc Source Repository REPOSITORY

https://github.com/star7th/showdoc/issues/1406

Security Fix Commit FIX COMMIT

https://github.com/star7th/showdoc/commit/49b992d4c548c8c615a92b6efe8a50c8f1083abf

Showdoc/showdoc Source Repository REPOSITORY

https://github.com/star7th/showdoc

Frequently Asked Questions

What is CVE-2021-36440?

CVE-2021-36440 is a security vulnerability in Showdoc/showdoc involving Unrestricted File Upload in ShowDoc v2.9.5 under CWE-434: Unrestricted Upload of File with Dangerous Type.

Which Showdoc/showdoc versions are affected?

Affected versions include releases prior to 2.9.6 across affected packages: showdoc/showdoc.

What version fixes CVE-2021-36440?

Upgrading to 2.9.6 (or the latest patched release for your respective branch) resolves the vulnerability.

Is showdoc/showdoc affected?

Yes, showdoc/showdoc is affected in releases prior to 2.9.6. Upgrade your dependency to 2.9.6 or later.

What is the CVSS score of CVE-2021-36440?

CVE-2021-36440 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

What CWE is associated with CVE-2021-36440?

CVE-2021-36440 is classified under CWE-434: Unrestricted Upload of File with Dangerous Type (The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.).

How can I check Packagist dependencies for CVE-2021-36440?

Run the dependency tree command: 'inspect dependencies for showdoc/showdoc'. 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-c442-3278-rhrg",
  "modified" : "2021-09-16T19:26:04Z",
  "published" : "2021-09-09T17:08:46Z",
  "aliases" : [ "CVE-2021-36440" ],
  "summary" : "Unrestricted File Upload in ShowDoc v2.9.5",
  "details" : "Unrestricted File Upload in ShowDoc v2.9.5 allows remote attackers to execute arbitrary code via the 'file_url' parameter in the component AdminUpdateController.class.php'.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "showdoc/showdoc"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.9.6"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-36440"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/star7th/showdoc/issues/1406"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/star7th/showdoc/commit/49b992d4c548c8c615a92b6efe8a50c8f1083abf"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/star7th/showdoc"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-434" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-09-09T13:18:05Z",
    "nvd_published_at" : "2021-09-08T21:15:00Z"
  }
}

CVSS V3

9.8 CRITICAL