CVE-2021-4000: Showdoc/showdoc Open Redirect Vulnerability

MODERATE
Advisory Identifier: GHSA-8c9x-wfgj-v78w
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CVSS 6.5
CWE-601
Published
Advisory Summary

CVE-2021-4000 is a MODERATE (CVSS 6.5) open redirect vulnerability (CWE-601: URL Redirection to Untrusted Site ('Open Redirect')) affecting Showdoc/showdoc libraries in the Packagist ecosystem. The issue involves open redirect in showdoc. Remediation is available in the latest vendor maintenance releases.

CVE-2021-4000 at a Glance

CVE Identifier CVE-2021-4000
GHSA Identifier GHSA-8c9x-wfgj-v78w
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-601: URL Redirection to Untrusted Site ('Open Redirect')
Affected Product Showdoc/showdoc
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/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 Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2021-4000

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: Latest secure release 
Upgrade showdoc/showdoc 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 showdoc/showdoc

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-4000, 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 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-601: URL Redirection to Untrusted Site ('Open Redirect'), where the web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect. 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

showdoc is vulnerable to URL Redirection to Untrusted Site

CVE-2021-4000 Affected Showdoc/showdoc Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
showdoc/showdoc
 Packagist
≤ 2.9.13

References

NVD — CVE-2021-4000 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-4000
Security Fix Commit FIX COMMIT
https://github.com/star7th/showdoc/commit/c7f10033eba5f2b5a537f9af9ba2379138e67138
Showdoc/showdoc Source Repository REPOSITORY
https://github.com/star7th/showdoc
huntr.dev/bounties/e4d803e0-3... WEB
https://huntr.dev/bounties/e4d803e0-3104-432c-80b3-34bc453c8962

Frequently Asked Questions

What is CVE-2021-4000?
CVE-2021-4000 is a security vulnerability in Showdoc/showdoc involving Open Redirect in showdoc under CWE-601: URL Redirection to Untrusted Site ('Open Redirect').
Which Showdoc/showdoc versions are affected?
Affected versions include releases prior to current release patches across affected packages: showdoc/showdoc.
What version fixes CVE-2021-4000?
Upgrading to current release patches (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 Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2021-4000?
CVE-2021-4000 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2021-4000?
CVE-2021-4000 is classified under CWE-601: URL Redirection to Untrusted Site ('Open Redirect') (The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.).
How can I check Packagist dependencies for CVE-2021-4000?
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-8c9x-wfgj-v78w",
  "modified" : "2021-12-06T21:57:44Z",
  "published" : "2021-12-16T15:31:58Z",
  "aliases" : [ "CVE-2021-4000" ],
  "summary" : "Open Redirect in showdoc",
  "details" : "showdoc is vulnerable to URL Redirection to Untrusted Site",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "showdoc/showdoc"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "2.9.13"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-4000"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/star7th/showdoc/commit/c7f10033eba5f2b5a537f9af9ba2379138e67138"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/star7th/showdoc"
  }, {
    "type" : "WEB",
    "url" : "https://huntr.dev/bounties/e4d803e0-3104-432c-80b3-34bc453c8962"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-601" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-12-06T21:57:44Z",
    "nvd_published_at" : "2021-12-03T11:15:00Z"
  }
}