Mermaid Architecture diagrams are vulnerable to prototype pollution
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Partial Red Hat: 3 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| mermaid-js | mermaid | 11.5.0 to before 11.16.1 | 11.16.1 | Patch available | CNA |
| — | mermaid (npm) | 11.5.0 to before 11.16.1 | 11.16.1 | Patch available | GHSA-3rrr-jr9j-h3q3 |
- mermaid Vendormermaid-js Affected 11.5.0 to before 11.16.1 Fixed in 11.16.1 Patch available CNA
- mermaid (npm) Vendor— Affected 11.5.0 to before 11.16.1 Fixed in 11.16.1 Patch available GHSA-3rrr-jr9j-h3q3
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mermaid_project:mermaid:*:*:*:*:*:*:*:* | — | — | mermaid-js |
- cpe:2.3:a:mermaid_project:mermaid:*:*:*:*:*:*:*:* Versions — — ·mermaid-js
Remediation
- Fix · CNA mermaid (mermaid-js) Fixed in 11.16.1
- Fix · GHSA-3rrr-jr9j-h3q3 mermaid (npm) Fixed in 11.16.1 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Build of Podman Desktop | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Dev Spaces | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-71437
- 2026-10-03 Alias added: GHSA-3rrr-jr9j-h3q3
References
Other 5
- https://github.com/mermaid-js/mermaid/security/advisories/GHSA-3rrr-jr9j-h3q3
- https://github.com/mermaid-js/mermaid/pull/8022
- https://github.com/mermaid-js/mermaid/commit/99af3fc35ef0a9a9c8c6314521344d67523ddccf
- https://github.com/mermaid-js/mermaid/releases/tag/[email protected]
- https://github.com/mermaid-js/mermaid
More mermaid-js vulnerabilities
- TI-2026-29778 Mermaid Gantt Charts are vulnerable to an Infinite Loop DoS CVSS 4.0MEDIUM 5.3
- TI-2025-34615 Mermaid improperly sanitizes of sequence diagram labels leading to XSS CVSS 4.0MEDIUM 5.3
- TI-2022-13152 Arbitrary `CSS` injection into the generated graph affecting the container HTML in mermaid.js CVSS 3.1MEDIUM 6.1
- TI-2024-25762 Cross-site Scripting in ZenUML CVSS 3.1MEDIUM 5.4
- TI-2026-29777 Mermaid: Improper sanitization of `classDef` in state diagrams leads to HTML injection CVSS 4.0MEDIUM 5.3
- TI-2025-34614 Mermaid does not properly sanitize architecture diagram iconText leading to XSS CVSS 4.0MEDIUM 5.1
Sources
- CVE-2026-71437 · CVE Program
- CVE-2026-71437 · NVD
- FIRST EPSS
- GHSA-3rrr-jr9j-h3q3 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-71437 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences