fix: strip direction override characters

Author: yadue

src/autolinker.ts

@@ -913,6 +913,8 @@ export default class Autolinker {
             textOrHtml = textOrHtml.replace(/</g, '&lt;').replace(/>/g, '&gt;');
         }
 
+        textOrHtml = this.stripUnsafeCharacters(textOrHtml);
+
         let matches = this.parse(textOrHtml),
             newHtml: string[] = [],
             lastIndex = 0;
@@ -1020,6 +1022,16 @@ export default class Autolinker {
 
         return tagBuilder;
     }
+
+    /**
+     * Strips characters considered as unsafe
+     * SNYK-AUTOLINKER-2438289
+     * @param text
+     * @private
+     */
+    private stripUnsafeCharacters(text: string) {
+        return text.replace(/[\u202a-\u202e, \u200e-\u200f]/g, '');
+    }
 }
 
 export interface AutolinkerConfig {

tests/autolinker-url.spec.ts

@@ -1265,4 +1265,30 @@ describe('Autolinker Url Matching -', () => {
             );
         });
     });
+
+    describe('unicode exploits', () => {
+        it('should strip out character direction override unicodes', () => {
+            expect(autolinker.link('foo.combar.com')).toBe(
+                '<a href="http://foo.combar.com">foo.combar.com</a>'
+            );
+            expect(autolinker.link('foo.com\u202Ebar.com')).toBe(
+                '<a href="http://foo.combar.com">foo.combar.com</a>'
+            );
+            expect(autolinker.link('foo.com\u202abar.com')).toBe(
+                '<a href="http://foo.combar.com">foo.combar.com</a>'
+            );
+            expect(autolinker.link('foo.com\u202bbar.com')).toBe(
+                '<a href="http://foo.combar.com">foo.combar.com</a>'
+            );
+            expect(autolinker.link('foo.com\u202cbar.com')).toBe(
+                '<a href="http://foo.combar.com">foo.combar.com</a>'
+            );
+            expect(autolinker.link('foo.com\u202dbar.com')).toBe(
+                '<a href="http://foo.combar.com">foo.combar.com</a>'
+            );
+            expect(autolinker.link('foo.com\u202ebar.com')).toBe(
+                '<a href="http://foo.combar.com">foo.combar.com</a>'
+            );
+        });
+    });
 });