CVE-2021-40978: Mkdocs Path Traversal Vulnerability

HIGH
Advisory Identifier: GHSA-qh9q-34h6-hcv9
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CVSS 7.5
CWE-12 CWE-22
Published
Advisory Summary

CVE-2021-40978 is a HIGH (CVSS 7.5) path traversal vulnerability (CWE-12: ASP.NET Misconfiguration: Missing Custom Error Page) affecting Mkdocs libraries in the PyPI ecosystem. The issue involves directory traversal in mkdocs. Remediation is available by upgrading affected packages to version 1.2.3.

CVE-2021-40978 at a Glance

CVE Identifier CVE-2021-40978
GHSA Identifier GHSA-qh9q-34h6-hcv9
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-12: ASP.NET Misconfiguration: Missing Custom Error Page
Affected Product Mkdocs
Package Ecosystem PyPI
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:H/I:N/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 High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2021-40978

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

mkdocs fixed: 1.2.3 
pip install mkdocs>=1.2.3
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 mkdocs

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2021-40978, inspect your installed packages using pip:

pip show mkdocs

Analyze the terminal output to locate any version of Mkdocs in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.2.3), your application is affected.

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

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-12: ASP.NET Misconfiguration: Missing Custom Error Page, where an asp .net application must enable custom error pages in order to prevent attackers from mining information from the framework's built-in responses. In Mkdocs, 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

The mkdocs 1.2.2 built-in dev-server allows directory traversal using the port 8000, enabling remote exploitation to obtain :sensitive information.

CVE-2021-40978 Affected Mkdocs Versions

1 component(s)
Fixed Versions:
1.2.3
Product / Package Ecosystem Affected Versions Fixed Version
mkdocs
pypi/mkdocs
PyPI
≥ 1.2.2
< 1.2.3
All 1 versions
1.2.2
1.2.3

References

NVD — CVE-2021-40978 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-40978
Mkdocs Source Repository REPOSITORY
https://github.com/mkdocs/mkdocs/issues/2601
Mkdocs Source Repository REPOSITORY
https://github.com/nisdn/CVE-2021-40978/issues/1
Mkdocs Source Repository REPOSITORY
https://github.com/mkdocs/mkdocs/pull/2604
Security Fix Commit FIX COMMIT
https://github.com/mkdocs/mkdocs/commit/1b15412f4caae476c262210315fd068d0521a833
Security Fix Commit FIX COMMIT
https://github.com/mkdocs/mkdocs/commit/57540911a0d632674dd23edec765189f96f84f6b
Mkdocs Source Repository REPOSITORY
https://github.com/mkdocs/mkdocs
Mkdocs Release RELEASE
https://github.com/mkdocs/mkdocs/releases/tag/1.2.3
Mkdocs Source Repository REPOSITORY
https://github.com/nisdn/CVE-2021-40978
Mkdocs Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/mkdocs/PYSEC-2021-878.yaml

Frequently Asked Questions

What is CVE-2021-40978?
CVE-2021-40978 is a security vulnerability in Mkdocs involving Directory traversal in mkdocs under CWE-12: ASP.NET Misconfiguration: Missing Custom Error Page.
Which Mkdocs versions are affected?
Affected versions include releases prior to 1.2.3 across affected packages: mkdocs.
What version fixes CVE-2021-40978?
Upgrading to 1.2.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is mkdocs affected?
Yes, mkdocs is affected in releases prior to 1.2.3. Upgrade your dependency to 1.2.3 or later.
What is the CVSS score of CVE-2021-40978?
CVE-2021-40978 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:H/I:N/A:N.
What CWE is associated with CVE-2021-40978?
CVE-2021-40978 is classified under CWE-12: ASP.NET Misconfiguration: Missing Custom Error Page (An ASP .NET application must enable custom error pages in order to prevent attackers from mining information from the framework's built-in responses.).
How can I check PyPI dependencies for CVE-2021-40978?
Run the dependency tree command: 'pip show mkdocs'. 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-qh9q-34h6-hcv9",
  "modified" : "2024-10-01T19:21:31Z",
  "published" : "2021-10-12T18:48:24Z",
  "aliases" : [ "CVE-2021-40978" ],
  "summary" : "Directory traversal in mkdocs",
  "details" : "The mkdocs 1.2.2 built-in dev-server allows directory traversal using the port 8000, enabling remote exploitation to obtain :sensitive information.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "mkdocs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.2.2"
      }, {
        "fixed" : "1.2.3"
      } ]
    } ],
    "versions" : [ "1.2.2" ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-40978"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mkdocs/mkdocs/issues/2601"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nisdn/CVE-2021-40978/issues/1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mkdocs/mkdocs/pull/2604"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mkdocs/mkdocs/commit/1b15412f4caae476c262210315fd068d0521a833"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mkdocs/mkdocs/commit/57540911a0d632674dd23edec765189f96f84f6b"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mkdocs/mkdocs"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mkdocs/mkdocs/releases/tag/1.2.3"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nisdn/CVE-2021-40978"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/mkdocs/PYSEC-2021-878.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-12", "CWE-22" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-10-08T21:41:01Z",
    "nvd_published_at" : "2021-10-07T14:15:00Z"
  }
}