From 68b2df83111c4cb55980dbca8f7d9c07bd65e5c0 Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Wed, 12 Aug 2026 09:55:59 +0300
Subject: [PATCH 1/2] Write 0 in the expiration time field for session cookies

curl and Wget ignore the line if this field is empty.
---
 Lib/http/cookiejar.py                         |  4 ++-
 Lib/test/test_http_cookiejar.py               | 29 +++++++++++++++++++
 ...6-08-12-09-30-00.gh-issue-61366.Wr7cKm.rst |  3 ++
 3 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2026-08-12-09-30-00.gh-issue-61366.Wr7cKm.rst

diff --git a/Lib/http/cookiejar.py b/Lib/http/cookiejar.py
index 81526cd544acfb..144db91a0f0317 100644
--- a/Lib/http/cookiejar.py
+++ b/Lib/http/cookiejar.py
@@ -2109,7 +2109,9 @@ def save(self, filename=None, ignore_discard=False, ignore_expires=False):
                 if cookie.expires is not None:
                     expires = str(cookie.expires)
                 else:
-                    expires = ""
+                    # curl and Wget use 0 for session cookies, and ignore
+                    # the line if this field is empty.
+                    expires = "0"
                 if cookie.value is None:
                     # cookies.txt regards 'Set-Cookie: foo' as a cookie
                     # with no name, whereas http.cookiejar regards it as a
diff --git a/Lib/test/test_http_cookiejar.py b/Lib/test/test_http_cookiejar.py
index 7c31cff56000b8..218181f1185365 100644
--- a/Lib/test/test_http_cookiejar.py
+++ b/Lib/test/test_http_cookiejar.py
@@ -2048,6 +2048,35 @@ def test_session_cookies(self):
             # we didn't have session cookies in the first place
         self.assertNotEqual(counter["session_before"], 0)
 
+    def test_save_session_cookies(self):
+        # Session cookies are saved with 0 in the expiration time field,
+        # as curl and Wget do (gh-61366).
+        filename = os_helper.TESTFN
+        self.addCleanup(os_helper.unlink, filename)
+        expires = int(time.time() + 3600)
+        c = MozillaCookieJar()
+        c.set_cookie(Cookie(0, "perm", "bar", None, False,
+                            "www.foo.com", True, False, "/", False, False,
+                            expires, False, None, None, {}))
+        c.set_cookie(Cookie(0, "session", "bar", None, False,
+                            "www.foo.com", True, False, "/", False, False,
+                            None, True, None, None, {}))
+        c.save(filename, ignore_discard=True)
+
+        saved = {}
+        with open(filename) as f:
+            for line in f:
+                if line.strip() and not line.startswith("#"):
+                    fields = line.split("\t")
+                    saved[fields[5]] = fields[4]
+        self.assertEqual(saved, {"perm": str(expires), "session": "0"})
+
+        # The saved file can be read back.
+        c = MozillaCookieJar()
+        c.revert(filename, ignore_discard=True)
+        self.assertEqual(sorted(cookie.name for cookie in c),
+                         ["perm", "session"])
+
     def test_load_session_cookies(self):
         # curl and Wget write 0 in the expires field for session cookies,
         # while we write an empty field.  Both should be read (gh-61366).
diff --git a/Misc/NEWS.d/next/Library/2026-08-12-09-30-00.gh-issue-61366.Wr7cKm.rst b/Misc/NEWS.d/next/Library/2026-08-12-09-30-00.gh-issue-61366.Wr7cKm.rst
new file mode 100644
index 00000000000000..9a6b634311b232
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-08-12-09-30-00.gh-issue-61366.Wr7cKm.rst
@@ -0,0 +1,3 @@
+:meth:`http.cookiejar.MozillaCookieJar.save` now writes ``0`` in the
+expiration time field for session cookies, as curl and Wget do.  Previously
+this field was left empty, and such lines were ignored by curl and Wget.

From 990501db303dc8fd5950f255eedb8081893473ea Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Wed, 12 Aug 2026 11:54:23 +0300
Subject: [PATCH 2/2] Update 2026-08-12-09-30-00.gh-issue-61366.Wr7cKm.rst

---
 .../next/Library/2026-08-12-09-30-00.gh-issue-61366.Wr7cKm.rst  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/Library/2026-08-12-09-30-00.gh-issue-61366.Wr7cKm.rst b/Misc/NEWS.d/next/Library/2026-08-12-09-30-00.gh-issue-61366.Wr7cKm.rst
index 9a6b634311b232..662d55f05abda6 100644
--- a/Misc/NEWS.d/next/Library/2026-08-12-09-30-00.gh-issue-61366.Wr7cKm.rst
+++ b/Misc/NEWS.d/next/Library/2026-08-12-09-30-00.gh-issue-61366.Wr7cKm.rst
@@ -1,3 +1,3 @@
-:meth:`http.cookiejar.MozillaCookieJar.save` now writes ``0`` in the
+:meth:`!http.cookiejar.MozillaCookieJar.save` now writes ``0`` in the
 expiration time field for session cookies, as curl and Wget do.  Previously
 this field was left empty, and such lines were ignored by curl and Wget.