CVE-2021-4172: Showdoc/showdoc Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-7x22-pmw5-66mq
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CVSS 5.4
CWE-79
Published
Advisory Summary

CVE-2021-4172 is a MODERATE (CVSS 5.4) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Showdoc/showdoc libraries in the Packagist ecosystem. The issue involves cross-site scripting in showdoc. Remediation is available by upgrading affected packages to version 2.10.2.

CVE-2021-4172 at a Glance

CVE Identifier CVE-2021-4172
GHSA Identifier GHSA-7x22-pmw5-66mq
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Showdoc/showdoc
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 5.4

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:R/S:C/C:L/I:L/A:N).

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

How to Fix CVE-2021-4172

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: 2.10.2 
Upgrade showdoc/showdoc to 2.10.2
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-2021-4172, 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 2.10.2), 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-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. 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

Stored XSS via upload attachment with format .svg in File Library.

CVE-2021-4172 Affected Showdoc/showdoc Versions

1 component(s)
Fixed Versions:
2.10.2
Product / Package Ecosystem Affected Versions Fixed Version
showdoc/showdoc
 Packagist
< 2.10.2
2.10.2

References

NVD — CVE-2021-4172 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-4172
Security Fix Commit FIX COMMIT
https://github.com/star7th/showdoc/commit/409c8a1208bbb847046a9496303192980f2e6219
Showdoc/showdoc Source Repository REPOSITORY
https://github.com/star7th/showdoc
huntr.dev/bounties/c041b693-8... WEB
https://huntr.dev/bounties/c041b693-877b-4456-b463-19e4c9456eee

Frequently Asked Questions

What is CVE-2021-4172?
CVE-2021-4172 is a security vulnerability in Showdoc/showdoc involving Cross-site Scripting in showdoc under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Showdoc/showdoc versions are affected?
Affected versions include releases prior to 2.10.2 across affected packages: showdoc/showdoc.
What version fixes CVE-2021-4172?
Upgrading to 2.10.2 (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 2.10.2. Upgrade your dependency to 2.10.2 or later.
What is the CVSS score of CVE-2021-4172?
CVE-2021-4172 has a CVSS v3.1 base score of 5.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2021-4172?
CVE-2021-4172 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check Packagist dependencies for CVE-2021-4172?
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-7x22-pmw5-66mq",
  "modified" : "2022-01-28T22:22:26Z",
  "published" : "2022-02-01T00:44:14Z",
  "aliases" : [ "CVE-2021-4172" ],
  "summary" : "Cross-site Scripting in showdoc",
  "details" : "Stored XSS via upload attachment with format .svg in File Library.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "showdoc/showdoc"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.10.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-4172"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/star7th/showdoc/commit/409c8a1208bbb847046a9496303192980f2e6219"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/star7th/showdoc"
  }, {
    "type" : "WEB",
    "url" : "https://huntr.dev/bounties/c041b693-877b-4456-b463-19e4c9456eee"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-01-28T22:22:26Z",
    "nvd_published_at" : "2022-01-22T12:15:00Z"
  }
}