Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. From version 11.5.0 until 11.16.1, Mermaid Architecture Diagrams are vulnerable to prototype pollution when a diagram defines a group with an id of __proto__. Because the group id is used directly as an object property key without validation, an attacker who can supply diagram text can pollute Object.prototype, potentially affecting the behavior of the embedding application. This issue is fixed in version 11.16.1.
History

Sun, 09 Aug 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-915
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L'}

threat_severity

Moderate


Fri, 07 Aug 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 07 Aug 2026 09:15:00 +0000

Type Values Removed Values Added
First Time appeared Mermaid Project
Mermaid Project mermaid
Vendors & Products Mermaid Project
Mermaid Project mermaid

Thu, 06 Aug 2026 22:15:00 +0000

Type Values Removed Values Added
Description Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. From version 11.5.0 until 11.16.1, Mermaid Architecture Diagrams are vulnerable to prototype pollution when a diagram defines a group with an id of __proto__. Because the group id is used directly as an object property key without validation, an attacker who can supply diagram text can pollute Object.prototype, potentially affecting the behavior of the embedding application. This issue is fixed in version 11.16.1.
Title Mermaid Architecture diagrams are vulnerable to prototype pollution
Weaknesses CWE-1321
References
Metrics cvssV4_0

{'score': 6.5, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:H/SI:H/SA:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-08-06T19:51:52.975Z

Updated: 2026-08-07T17:37:35.933Z

Reserved: 2026-08-06T16:28:51.183Z

Link: CVE-2026-71437

cve-icon Vulnrichment

Updated: 2026-08-07T17:37:31.821Z

cve-icon NVD

No data.

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-08-06T19:51:52Z

Links: CVE-2026-71437 - Bugzilla