CVE-2026-73159: medium-severity vulnerability in MISP cti-transmute

Affected versions of cti-transmute allow a tag's icon value to be stored and later interpolated into HTML through Vue's v-html. The helper mapIcon() previously constructed an HTML string directly from the icon value: <i class="fas fa-${name}"></i> Because the icon is user-supplied, a crafted value could break out of the intended markup and inject attacker-controlled HTML. When the affected tag was later rendered, including on the administrative triage interface, the payload could execute in the viewer's browser. The patch mitigates the issue at multiple layers: v-html is replaced with Vue :class binding, mapIcon() now returns only a constrained FontAwesome class string, and the backend validates icons against the FontAwesome catalogue or a strict [a-z0-9-]{1,40} slug pattern before storing them.