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TI-2026-36923 Aliases CVE-2026-50159GHSA-6x64-9x62-f2gx

Mermaid allows CSS injection applying to sibling elements of the diagram

Priority LOW 25CWE-94Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Passive
Attack complexity
Low
Attack requirements
None
Impact type
Code execution
Confidentiality · integrity · availability
None · Low · None
Fix status
Partial Red Hat: 2 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-94.

Summary

Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Prior to 10.9.8 and 11.16.1, Mermaid is vulnerable to CSS injection via sibling combinator selectors generated from diagram-supplied class or id names. An attacker who can supply diagram text can inject arbitrary CSS into the rendered page, potentially altering the appearance or behavior of unrelated page elements. This issue is fixed in versions 10.9.8 and 11.16.1.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00603 49th percentileScored 2026-11-07
Fix Partial mermaid (mermaid-js): 10.9.8, 11.16.1mermaid (npm): 11.16.1, 10.9.8Red Hat: 2 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
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

VendorProductAffected versionsFixed inStatusSource
mermaid-jsmermaidbefore 10.9.8; 11.0.0-alpha.1 to before 11.16.110.9.8, 11.16.1Patch availableCNA
—mermaid (npm)11.0.0-alpha.1 to before 11.16.111.16.1Patch availableGHSA-6x64-9x62-f2gx
—mermaid (npm)before 10.9.810.9.8Patch availableGHSA-6x64-9x62-f2gx
  • mermaid Vendormermaid-js Affected before 10.9.8; 11.0.0-alpha.1 to before 11.16.1 Fixed in 10.9.8, 11.16.1 Patch available CNA
  • mermaid (npm) Vendor— Affected 11.0.0-alpha.1 to before 11.16.1 Fixed in 11.16.1 Patch available GHSA-6x64-9x62-f2gx
  • mermaid (npm) Vendor— Affected before 10.9.8 Fixed in 10.9.8 Patch available GHSA-6x64-9x62-f2gx

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
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 10.9.8, 11.16.1
  • Fix · GHSA-6x64-9x62-f2gx mermaid (npm) Fixed in 11.16.1 Advisory →
  • Fix · GHSA-6x64-9x62-f2gx mermaid (npm) Fixed in 10.9.8 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat OpenShift AI (RHOAI)AffectedNo fix yet: Fix deferred
Red Hat OpenShift Dev SpacesAffectedNo fix yet: Fix deferred
Not affected: 1 product
  • Red Hat Build of Podman Desktop

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-50159
  2. 2026-10-03 Alias added: GHSA-6x64-9x62-f2gx

References

Other 7

  • 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-2026-50057 Mermaid Architecture diagrams are vulnerable to prototype pollution CVSS 4.0MEDIUM 6.5
  • 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
See all 14 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences