diff --git a/test/unit/clitests.json b/test/unit/clitests.json
index 744fb63a8..3ae55b789 100644
--- a/test/unit/clitests.json
+++ b/test/unit/clitests.json
@@ -42,6 +42,7 @@
     "pdf_find_controller_spec.js",
     "pdf_find_utils_spec.js",
     "pdf_history_spec.js",
+    "pdf_link_service_spec.js",
     "pdf_spec.js",
     "pdf_viewer.component_spec.js",
     "pdf_viewer_spec.js",
diff --git a/test/unit/jasmine-boot.js b/test/unit/jasmine-boot.js
index 4f04beb73..e151d7ebb 100644
--- a/test/unit/jasmine-boot.js
+++ b/test/unit/jasmine-boot.js
@@ -85,6 +85,7 @@ async function initializePDFJS(callback) {
       "pdfjs-test/unit/pdf_find_controller_spec.js",
       "pdfjs-test/unit/pdf_find_utils_spec.js",
       "pdfjs-test/unit/pdf_history_spec.js",
+      "pdfjs-test/unit/pdf_link_service_spec.js",
       "pdfjs-test/unit/pdf_spec.js",
       "pdfjs-test/unit/pdf_viewer.component_spec.js",
       "pdfjs-test/unit/pdf_viewer_spec.js",
diff --git a/test/unit/pdf_link_service_spec.js b/test/unit/pdf_link_service_spec.js
new file mode 100644
index 000000000..f13794b99
--- /dev/null
+++ b/test/unit/pdf_link_service_spec.js
@@ -0,0 +1,115 @@
+/* Copyright 2026 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { PDFLinkService } from "../../web/pdf_link_service.js";
+
+describe("PDFLinkService", function () {
+  describe("addLinkAttributes", function () {
+    function createLinkService({ externalLinkEnabled = true } = {}) {
+      const linkService = new PDFLinkService();
+      linkService.externalLinkEnabled = externalLinkEnabled;
+      return linkService;
+    }
+
+    // Use a plain object instead of a real DOM element so tests run in Node.js.
+    function createLink() {
+      return { href: "", title: "", target: "", rel: "" };
+    }
+
+    it("sets href and title for a plain URL", function () {
+      const linkService = createLinkService();
+      const link = createLink();
+
+      linkService.addLinkAttributes(link, "https://example.com/path");
+
+      expect(link.href).toEqual("https://example.com/path");
+      expect(link.title).toEqual("https://example.com/path");
+    });
+
+    it("strips userinfo from the title to prevent hostname spoofing", function () {
+      const linkService = createLinkService();
+      const link = createLink();
+
+      // URL with username that looks like a trusted domain.
+      linkService.addLinkAttributes(
+        link,
+        "https://trusted.example@attacker.example/path"
+      );
+
+      expect(link.href).toEqual(
+        "https://trusted.example@attacker.example/path"
+      );
+      expect(link.title).toEqual("https://attacker.example/path");
+    });
+
+    it("strips username and password from the title", function () {
+      const linkService = createLinkService();
+      const link = createLink();
+
+      linkService.addLinkAttributes(
+        link,
+        "https://user:password@example.com/path"
+      );
+
+      expect(link.href).toEqual("https://user:password@example.com/path");
+      expect(link.title).toEqual("https://example.com/path");
+    });
+
+    it("strips only username (no password) from the title", function () {
+      const linkService = createLinkService();
+      const link = createLink();
+
+      linkService.addLinkAttributes(link, "https://user@example.com/page");
+
+      expect(link.href).toEqual("https://user@example.com/page");
+      expect(link.title).toEqual("https://example.com/page");
+    });
+
+    it("does not alter the title when there is no userinfo", function () {
+      const linkService = createLinkService();
+      const link = createLink();
+
+      linkService.addLinkAttributes(
+        link,
+        "https://example.com/path?q=1#anchor"
+      );
+
+      expect(link.title).toEqual("https://example.com/path?q=1#anchor");
+    });
+
+    it("disables the link and prefixes the title when externalLinkEnabled is false", function () {
+      const linkService = createLinkService({ externalLinkEnabled: false });
+      const link = createLink();
+
+      linkService.addLinkAttributes(link, "https://example.com/path");
+
+      expect(link.href).toEqual("");
+      expect(link.title).toEqual("Disabled: https://example.com/path");
+    });
+
+    it("strips userinfo from the title even when the link is disabled", function () {
+      const linkService = createLinkService({ externalLinkEnabled: false });
+      const link = createLink();
+
+      linkService.addLinkAttributes(
+        link,
+        "https://trusted.example@attacker.example/path"
+      );
+
+      expect(link.href).toEqual("");
+      expect(link.title).toEqual("Disabled: https://attacker.example/path");
+    });
+  });
+});
diff --git a/web/pdf_link_service.js b/web/pdf_link_service.js
index cefced69c..2b592d62b 100644
--- a/web/pdf_link_service.js
+++ b/web/pdf_link_service.js
@@ -266,11 +266,21 @@ class PDFLinkService {
     const target = newWindow ? LinkTarget.BLANK : this.externalLinkTarget,
       rel = this.externalLinkRel;
 
+    // Strip userinfo (user:password@) from URLs used for display, to prevent
+    // phishing via hostname-spoofing (e.g. https://trusted.example@attacker.example/).
+    let displayUrl = url;
+    const parsedUrl = URL.parse(url);
+    if (parsedUrl?.username || parsedUrl?.password) {
+      parsedUrl.username = parsedUrl.password = "";
+      displayUrl = parsedUrl.href;
+    }
+
     if (this.externalLinkEnabled) {
-      link.href = link.title = url;
+      link.href = url;
+      link.title = displayUrl;
     } else {
       link.href = "";
-      link.title = `Disabled: ${url}`;
+      link.title = `Disabled: ${displayUrl}`;
       link.onclick = () => false;
     }