title: Arbitrary HTML injection in discourse-mermaid-theme-component
description: Discourse Mermaid (discourse-mermaid-theme-component) allows users of Discourse, open-source forum software, to create graphs using the Mermaid syntax. Users of discourse-mermaid-theme-component version 1.0.0 who can create posts are able to inject arbitrary HTML on that post. The issue has been fixed on the `main` branch of the GitHub repository, with 1.1.0 named as a patched version. Admins can update the theme component through the admin UI. As a workaround, admins can temporarily disable discourse-mermaid-theme-component.
problem types: CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
affected:
{
vendor: discourse
product: discourse-mermaid-theme-component
versions:
version: = 1.0.0, status: affected
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 5
baseSeverity: MEDIUM
confidentialityImpact: LOW
integrityImpact: NONE
privilegesRequired: LOW
scope: CHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
version: 3.1
]