CVE-2020-12827:Path Traversal Vulnerability in MJML's mj-include Directive

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Description Preview

MJML versions prior to 4.6.3 contain a path traversal vulnerability (CWE-22) that allows attackers to read arbitrary files from the server's filesystem when processing the mj-include directive within an MJML document. This vulnerability could potentially expose sensitive information or configuration files depending on the server's setup and permissions.

Overview

MJML (Mailjet Markup Language) is a markup language designed to simplify the creation of responsive email templates. The vulnerability exists in the mj-include component, which allows users to include external MJML files within their templates. In versions 4.6.2 and earlier, the path parameter of the mj-include directive is not properly validated, allowing attackers to use directory traversal sequences (such as "../") to access files outside the intended directory. This could lead to unauthorized access to sensitive files on the server where MJML is being processed, potentially exposing configuration files, credentials, or other confidential information.

Remediation

To remediate this vulnerability, users should:

  1. Update to MJML version 4.6.3 or later, which contains the fix for this vulnerability.
  2. If immediate updating is not possible, implement additional validation for file paths in your application layer before passing them to MJML.
  3. Consider implementing a whitelist approach for includable files or restricting the directories that can be accessed by the MJML processor.
  4. Run MJML with minimal privileges and in a sandboxed environment when processing untrusted input.
  5. Monitor for suspicious activity that might indicate exploitation attempts of this vulnerability.

The fix implemented in version 4.6.3 prevents directory traversal by properly validating and sanitizing file paths before accessing files.

References

  1. MJML 4.6.3 Release Notes: https://github.com/mjmlio/mjml/releases/tag/v4.6.3
  2. Patch Commit: https://github.com/mjmlio/mjml/commit/30e29ed2cdaec8684d60a6d12ea07b611c765a12
  3. Exploit Details: http://packetstormsecurity.com/files/158111/MJML-4.6.2-Path-Traversal.html
  4. Full Disclosure Mailing List: http://seclists.org/fulldisclosure/2020/Jun/23
  5. MJML Community Page: https://mjml.io/community
  6. MJML Twitter Account: https://twitter.com/mjmlio

Industry ExposureMost to least
This section illustrates the prevalence of a specific Common Vulnerabilities and Exposures (CVE) across various industries based on customer reports. The ranking displays industries from the most to least affected by this particular vulnerability, offering valuable insight into where this CVE has been most frequently observed. This information can help organizations within these sectors prioritize their security efforts, understand their relative risk exposure compared to their peers, and focus remediation strategies where they are most needed. By understanding the industry-specific impact, organizations can make more informed decisions regarding patching, resource allocation, and overall risk management related to this CVE.

  1. Accommodation & Food Services: Low
    Accommodation & Food Services
  2. Administrative, Support, Waste Management & Remediation Services: Low
    Administrative, Support, Waste Management & Remediation Services
  3. Agriculture, Forestry Fishing & Hunting: Low
    Agriculture, Forestry Fishing & Hunting
  4. Arts, Entertainment & Recreation: Low
    Arts, Entertainment & Recreation
  5. Construction: Low
    Construction
  6. Educational Services: Low
    Educational Services
  7. Finance and Insurance: Low
    Finance and Insurance
  8. Health Care & Social Assistance: Low
    Health Care & Social Assistance
  9. Information: Low
    Information
  10. Management of Companies & Enterprises: Low
    Management of Companies & Enterprises
  11. Manufacturing: Low
    Manufacturing
  12. Mining: Low
    Mining
  13. Other Services (except Public Administration): Low
    Other Services (except Public Administration)
  14. Professional, Scientific, & Technical Services: Low
    Professional, Scientific, & Technical Services
  15. Public Administration: Low
    Public Administration
  16. Real Estate Rental & Leasing: Low
    Real Estate Rental & Leasing
  17. Retail Trade: Low
    Retail Trade
  18. Transportation & Warehousing: Low
    Transportation & Warehousing
  19. Utilities: Low
    Utilities
  20. Wholesale Trade: Low
    Wholesale Trade

Focus on What Matters

  1. See Everything.
  2. Identify True Risk.
  3. Proactively Mitigate Threats.

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