CVE-2021-23422: Bikeshed OS Command Injection Vulnerability

HIGH
Advisory Identifier: GHSA-87cj-px37-rc3x
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CVSS 7.8
CWE-78
Published
Advisory Summary

CVE-2021-23422 is a HIGH (CVSS 7.8) os command injection vulnerability (CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')) affecting Bikeshed libraries in the PyPI ecosystem. The issue involves os command injection in bikeshed. Remediation is available by upgrading affected packages to version 3.0.0.

CVE-2021-23422 at a Glance

CVE Identifier CVE-2021-23422
GHSA Identifier GHSA-87cj-px37-rc3x
Severity HIGH
CVSS v3.1 Base Score 7.8
CWE Classification CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Affected Product Bikeshed
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).

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

How to Fix CVE-2021-23422

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

bikeshed fixed: 3.0.0 
pip install bikeshed>=3.0.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show bikeshed

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2021-23422, inspect your installed packages using pip:

pip show bikeshed

Analyze the terminal output to locate any version of Bikeshed in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.0.0), your application is affected.

Note: The pip show bikeshed command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'), where the product constructs all or part of an os command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended os command when it is sent to a downstream component. In Bikeshed, 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

This affects the package bikeshed before 3.0.0. This can occur when an untrusted source file containing Inline Tag Command metadata is processed. When an arbitrary OS command is executed, the command output would be included in the HTML output.

CVE-2021-23422 Affected Bikeshed Versions

1 component(s)
Fixed Versions:
3.0.0
Product / Package Ecosystem Affected Versions Fixed Version
bikeshed
pypi/bikeshed
PyPI
< 3.0.0
3.0.0

References

NVD — CVE-2021-23422 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-23422
Security Fix Commit FIX COMMIT
https://github.com/tabatkins/bikeshed/commit/b2f668fca204260b1cad28d5078e93471cb6b2dd
Bikeshed Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/bikeshed/PYSEC-2021-116.yaml
Bikeshed Source Repository REPOSITORY
https://github.com/tabatkins/bikeshed
snyk.io/vuln/snyk-python-bi... WEB
https://snyk.io/vuln/SNYK-PYTHON-BIKESHED-1537646

Frequently Asked Questions

What is CVE-2021-23422?
CVE-2021-23422 is a security vulnerability in Bikeshed involving OS Command Injection in bikeshed under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection').
Which Bikeshed versions are affected?
Affected versions include releases prior to 3.0.0 across affected packages: bikeshed.
What version fixes CVE-2021-23422?
Upgrading to 3.0.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is bikeshed affected?
Yes, bikeshed is affected in releases prior to 3.0.0. Upgrade your dependency to 3.0.0 or later.
What is the CVSS score of CVE-2021-23422?
CVE-2021-23422 has a CVSS v3.1 base score of 7.8 (HIGH) with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2021-23422?
CVE-2021-23422 is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') (The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.).
How can I check PyPI dependencies for CVE-2021-23422?
Run the dependency tree command: 'pip show bikeshed'. 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-87cj-px37-rc3x",
  "modified" : "2024-09-04T21:12:35Z",
  "published" : "2021-08-30T16:25:35Z",
  "aliases" : [ "CVE-2021-23422" ],
  "summary" : "OS Command Injection in bikeshed",
  "details" : "This affects the package bikeshed before 3.0.0. This can occur when an untrusted source file containing Inline Tag Command metadata is processed. When an arbitrary OS command is executed, the command output would be included in the HTML output.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "bikeshed"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.0.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-23422"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/tabatkins/bikeshed/commit/b2f668fca204260b1cad28d5078e93471cb6b2dd"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/bikeshed/PYSEC-2021-116.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/tabatkins/bikeshed"
  }, {
    "type" : "WEB",
    "url" : "https://snyk.io/vuln/SNYK-PYTHON-BIKESHED-1537646"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-78" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-26T15:58:50Z",
    "nvd_published_at" : "2021-08-16T08:15:00Z"
  }
}