From 9c33a0390a29f4d28b7a25eed2161edfb6a46e9a Mon Sep 17 00:00:00 2001
From: Sankalp Thakur <sankalphimself@gmail.com>
Date: Fri, 18 Sep 2026 01:28:54 +0000
Subject: [PATCH] gh-157692: Isolate saved PATH state in venv batch scripts

---
 Lib/test/test_venv.py                         | 30 +++++++++++++++++++
 Lib/venv/scripts/nt/activate.bat              |  4 +--
 Lib/venv/scripts/nt/deactivate.bat            |  6 ++--
 ...09-18-01-30-00.gh-issue-157692.BatPath.rst |  4 +++
 4 files changed, 39 insertions(+), 5 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2026-09-18-01-30-00.gh-issue-157692.BatPath.rst

diff --git a/Lib/test/test_venv.py b/Lib/test/test_venv.py
index 2f30d3108021dc..a3343dbb710cd1 100644
--- a/Lib/test/test_venv.py
+++ b/Lib/test/test_venv.py
@@ -870,6 +870,36 @@ def test_special_chars_windows(self):
         self.assertTrue(env_name.encode() in lines[0])
         self.assertEndsWith(lines[1], env_name.encode())
 
+    @unittest.skipUnless(os.name == 'nt', 'only relevant on Windows')
+    def test_activate_bat_preserves_foreign_path(self):
+        # gh-157692: cmd.exe and POSIX shells must not share saved PATH state.
+        venv.create(self.env_dir)
+        activate = self.get_env_file(self.bindir, 'activate.bat')
+        deactivate = self.get_env_file(self.bindir, 'deactivate.bat')
+        test_batch = self.get_env_file('test_saved_path.bat')
+        with open(test_batch, 'w') as f:
+            f.write('@echo off\n'
+                    'set "_OLD_VIRTUAL_PATH=/posix/saved/path"\n'
+                    'set "_OLD_VIRTUAL_PATH_BAT="\n'
+                    'path\n'
+                    f'call "{activate}"\n'
+                    'path\n'
+                    f'call "{activate}"\n'
+                    'path\n'
+                    f'call "{deactivate}"\n'
+                    'path\n'
+                    'echo FOREIGN:%_OLD_VIRTUAL_PATH%\n')
+        out, err = check_output([test_batch], encoding='oem')
+        paths = [line.partition('=')[2] for line in out.splitlines()
+                 if line.upper().startswith('PATH=')]
+        self.assertEqual(len(paths), 4, out)
+        original, active, repeated, restored = paths
+        self.assertEqual(active,
+                         os.path.join(self.env_dir, self.bindir) + ';' + original)
+        self.assertEqual(repeated, active)
+        self.assertEqual(restored, original)
+        self.assertIn('FOREIGN:/posix/saved/path', out.splitlines())
+
     @unittest.skipUnless(os.name == 'nt', 'only relevant on Windows')
     def test_unicode_in_batch_file(self):
         """
diff --git a/Lib/venv/scripts/nt/activate.bat b/Lib/venv/scripts/nt/activate.bat
index 4a3e791abb86bd..27dccebed8cf4f 100644
--- a/Lib/venv/scripts/nt/activate.bat
+++ b/Lib/venv/scripts/nt/activate.bat
@@ -19,8 +19,8 @@
 @if defined PYTHONHOME @set _OLD_VIRTUAL_PYTHONHOME=%PYTHONHOME%
 @set PYTHONHOME=
 
-@if defined _OLD_VIRTUAL_PATH @set PATH=%_OLD_VIRTUAL_PATH%
-@if not defined _OLD_VIRTUAL_PATH @set _OLD_VIRTUAL_PATH=%PATH%
+@if defined _OLD_VIRTUAL_PATH_BAT @set PATH=%_OLD_VIRTUAL_PATH_BAT%
+@if not defined _OLD_VIRTUAL_PATH_BAT @set _OLD_VIRTUAL_PATH_BAT=%PATH%
 
 @set "PATH=%VIRTUAL_ENV%\__VENV_BIN_NAME__;%PATH%"
 @set "VIRTUAL_ENV_PROMPT=__VENV_PROMPT__"
diff --git a/Lib/venv/scripts/nt/deactivate.bat b/Lib/venv/scripts/nt/deactivate.bat
index 4a04fb7c0bed44..35489973f063d9 100644
--- a/Lib/venv/scripts/nt/deactivate.bat
+++ b/Lib/venv/scripts/nt/deactivate.bat
@@ -8,11 +8,11 @@
     @set _OLD_VIRTUAL_PYTHONHOME=
 )
 
-@if defined _OLD_VIRTUAL_PATH (
-    @set "PATH=%_OLD_VIRTUAL_PATH%"
+@if defined _OLD_VIRTUAL_PATH_BAT (
+    @set "PATH=%_OLD_VIRTUAL_PATH_BAT%"
 )
 
-@set _OLD_VIRTUAL_PATH=
+@set _OLD_VIRTUAL_PATH_BAT=
 
 @set VIRTUAL_ENV=
 @set VIRTUAL_ENV_PROMPT=
diff --git a/Misc/NEWS.d/next/Library/2026-09-18-01-30-00.gh-issue-157692.BatPath.rst b/Misc/NEWS.d/next/Library/2026-09-18-01-30-00.gh-issue-157692.BatPath.rst
new file mode 100644
index 00000000000000..bc469df47e0fbb
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-09-18-01-30-00.gh-issue-157692.BatPath.rst
@@ -0,0 +1,4 @@
+Use separate saved ``PATH`` state for the Windows batch activation
+scripts in :mod:`venv`. This prevents a POSIX shell started from an
+activated command prompt from restoring a Windows-format ``PATH``
+when it activates a virtual environment.