CVE-2026-73161: medium-severity vulnerability in MISP cti-transmute

Affected versions of cti-transmute improperly handle conversion-table values passed through the search highlighting feature. The highlight() function previously returned the underlying text directly when no search query was supplied, or performed a regex replacement that inserted <mark> tags without first escaping the original content. Because the resulting value is used by an HTML-rendering sink, malicious markup contained in conversion data could be interpreted as HTML rather than displayed as text. The fix introduces a shared highlightMatches() helper that first converts special characters such as <, >, &, and quotes into HTML entities. Only after escaping does the code insert the application-controlled <mark> element used for search highlighting.