🛡️ Sentinel: Fix XSS vulnerability in markdown link sanitization

src/components/chat/message-bubble.test.tsx

@@ -79,4 +79,29 @@ describe("MessageBubble Link Sanitization", () => {
     expect(links[1].getAttribute("href")).toBe("#");
     expect(links[2].getAttribute("href")).toBe("#");
   });
+
+  it("should sanitize obfuscated protocols and non-allowlisted schemes to #", () => {
+    const message = {
+      id: "3",
+      role: "assistant",
+      content:
+        "Obfuscated: [Tab XSS](<java\tscript:alert(1)>), [Blob](blob:text/html,test), and [File](file:///etc/passwd).",
+      parts: [
+        {
+          type: "text",
+          text: "Obfuscated: [Tab XSS](<java\tscript:alert(1)>), [Blob](blob:text/html,test), and [File](file:///etc/passwd).",
+        },
+      ],
+    } as any;
+
+    const { container } = render(
+      <MessageBubble {...defaultProps} message={message} />,
+    );
+
+    const links = container.querySelectorAll("a");
+    expect(links.length).toBe(3);
+    expect(links[0].getAttribute("href")).toBe("#");
+    expect(links[1].getAttribute("href")).toBe("#");
+    expect(links[2].getAttribute("href")).toBe("#");
+  });
 });

src/components/chat/message-bubble.tsx

@@ -17,11 +17,24 @@ const selectElementText = (target: HTMLElement) => {
   selection?.addRange(range);
 };
 
+const isSafeUrl = (href?: string): boolean => {
+  if (!href) return false;
+  // Normalize URL by stripping control characters and whitespace before protocol validation
+  /* eslint-disable-next-line no-control-regex */
+  const controlChars = /[\u0000-\u0020\u007F-\u009F]/g;
+  const normalized = href.replace(controlChars, "");
+  return (
+    normalized.startsWith("#") ||
+    normalized.startsWith("/") ||
+    /^(https?|mailto|tel):/i.test(normalized)
+  );
+};
+
 const markdownComponents = {
   a: ({ href, children }: { href?: string; children?: React.ReactNode }) => {
     const isHash = href?.startsWith("#");
-    // Prevent prompt injection leading to XSS via javascript:, data:, or vbscript: protocols
-    const isSafe = href && !/^(javascript|data|vbscript):/i.test(href.trim());
+    // Prevent prompt injection leading to XSS by enforcing a strict protocol allowlist
+    const isSafe = isSafeUrl(href);
     const isExternal = !isHash;
     return (
       <a