diff --git a/packages/mermaid/src/diagrams/class/classDb.ts b/packages/mermaid/src/diagrams/class/classDb.ts
index 0e9b67dc9..7e116aada 100644
--- a/packages/mermaid/src/diagrams/class/classDb.ts
+++ b/packages/mermaid/src/diagrams/class/classDb.ts
@@ -26,6 +26,7 @@ import type {
 } from './classTypes.js';
 import type { Node, Edge } from '../../rendering-util/types.js';
 import type { DiagramDB } from '../../diagram-api/types.js';
+import DOMPurify from 'dompurify';
 
 const MERMAID_DOM_ID_PREFIX = 'classId-';
 let classCounter = 0;
@@ -504,7 +505,7 @@ export class ClassDB implements DiagramDB {
         const rect = (event.currentTarget as Element).getBoundingClientRect();
         tooltipElem.transition().duration(200).style('opacity', '.9');
         tooltipElem
-          .html(this.escapeHtml(title).replace(/&lt;br\/&gt;/g, '<br/>'))
+          .html(DOMPurify.sanitize(title))
           .style('left', `${window.scrollX + rect.left + rect.width / 2}px`)
           .style('top', `${window.scrollY + rect.bottom + 4}px`);
 
diff --git a/packages/mermaid/src/diagrams/flowchart/flowDb.ts b/packages/mermaid/src/diagrams/flowchart/flowDb.ts
index 0c2ef886c..7c389d65c 100644
--- a/packages/mermaid/src/diagrams/flowchart/flowDb.ts
+++ b/packages/mermaid/src/diagrams/flowchart/flowDb.ts
@@ -27,7 +27,7 @@ import type {
   FlowVertex,
   FlowVertexTypeParam,
 } from './types.js';
-
+import DOMPurify from 'dompurify';
 interface LinkData {
   id: string;
 }
@@ -596,7 +596,7 @@ You have to call mermaid.initialize.`
           .text(el.attr('title'))
           .style('left', window.scrollX + rect.left + (rect.right - rect.left) / 2 + 'px')
           .style('top', window.scrollY + rect.bottom + 'px');
-        tooltipElem.html(tooltipElem.html().replace(/&lt;br\/&gt;/g, '<br/>'));
+        tooltipElem.html(DOMPurify.sanitize(title));
         el.classed('hover', true);
       })
       .on('mouseout', (e: MouseEvent) => {