File CVE-2026-4519-webbrowser-open-dashes.patch of Package python311

From 44f1cc679123978895a21b424ab9678bf86b4c78 Mon Sep 17 00:00:00 2001
From: Seth Michael Larson <seth@python.org>
Date: Fri, 20 Mar 2026 09:47:13 -0500
Subject: [PATCH] gh-143930: Reject leading dashes in webbrowser URLs

(cherry picked from commit 82a24a4442312bdcfc4c799885e8b3e00990f02b)
---
 Lib/test/test_webbrowser.py                                              |    5 +++
 Lib/webbrowser.py                                                        |   14 ++++++++++
 Misc/NEWS.d/next/Security/2026-01-16-12-04-49.gh-issue-143930.zYC5x3.rst |    1 
 3 files changed, 20 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Security/2026-01-16-12-04-49.gh-issue-143930.zYC5x3.rst

Index: Python-3.11.15/Lib/test/test_webbrowser.py
===================================================================
--- Python-3.11.15.orig/Lib/test/test_webbrowser.py	2026-03-27 20:08:53.792496478 +0100
+++ Python-3.11.15/Lib/test/test_webbrowser.py	2026-03-27 20:08:56.539400295 +0100
@@ -59,6 +59,11 @@
                    options=[],
                    arguments=[URL])
 
+    def test_reject_dash_prefixes(self):
+        browser = self.browser_class(name=CMD_NAME)
+        with self.assertRaises(ValueError):
+            browser.open(f"--key=val {URL}")
+
 
 class BackgroundBrowserCommandTest(CommandTestMixin, unittest.TestCase):
 
Index: Python-3.11.15/Lib/webbrowser.py
===================================================================
--- Python-3.11.15.orig/Lib/webbrowser.py	2026-03-27 20:08:54.301026314 +0100
+++ Python-3.11.15/Lib/webbrowser.py	2026-03-27 20:08:56.539584483 +0100
@@ -154,6 +154,12 @@
     def open_new_tab(self, url):
         return self.open(url, 2)
 
+    @staticmethod
+    def _check_url(url):
+        """Ensures that the URL is safe to pass to subprocesses as a parameter"""
+        if url and url.lstrip().startswith("-"):
+            raise ValueError(f"Invalid URL: {url}")
+
 
 class GenericBrowser(BaseBrowser):
     """Class for all browsers started with a command
@@ -171,6 +177,7 @@
 
     def open(self, url, new=0, autoraise=True):
         sys.audit("webbrowser.open", url)
+        self._check_url(url)
         cmdline = [self.name] + [arg.replace("%s", url)
                                  for arg in self.args]
         try:
@@ -191,6 +198,7 @@
         cmdline = [self.name] + [arg.replace("%s", url)
                                  for arg in self.args]
         sys.audit("webbrowser.open", url)
+        self._check_url(url)
         try:
             if sys.platform[:3] == 'win':
                 p = subprocess.Popen(cmdline)
@@ -256,6 +264,7 @@
 
     def open(self, url, new=0, autoraise=True):
         sys.audit("webbrowser.open", url)
+        self._check_url(url)
         if new == 0:
             action = self.remote_action
         elif new == 1:
@@ -357,6 +366,7 @@
 
     def open(self, url, new=0, autoraise=True):
         sys.audit("webbrowser.open", url)
+        self._check_url(url)
         # XXX Currently I know no way to prevent KFM from opening a new win.
         if new == 2:
             action = "newTab"
@@ -441,6 +451,7 @@
 
     def open(self, url, new=0, autoraise=True):
         sys.audit("webbrowser.open", url)
+        self._check_url(url)
         if new:
             ok = self._remote("LOADNEW " + url)
         else:
@@ -604,6 +615,7 @@
     class WindowsDefault(BaseBrowser):
         def open(self, url, new=0, autoraise=True):
             sys.audit("webbrowser.open", url)
+            self._check_url(url)
             try:
                 os.startfile(url)
             except OSError:
@@ -636,6 +648,7 @@
 
         def open(self, url, new=0, autoraise=True):
             sys.audit("webbrowser.open", url)
+            self._check_url(url)
             assert "'" not in url
             # hack for local urls
             if not ':' in url:
@@ -688,6 +701,7 @@
 
         def open(self, url, new=0, autoraise=True):
             sys.audit("webbrowser.open", url)
+            self._check_url(url)
             if self.name == 'default':
                 script = 'open location "%s"' % url.replace('"', '%22') # opens in default browser
             else:
Index: Python-3.11.15/Misc/NEWS.d/next/Security/2026-01-16-12-04-49.gh-issue-143930.zYC5x3.rst
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ Python-3.11.15/Misc/NEWS.d/next/Security/2026-01-16-12-04-49.gh-issue-143930.zYC5x3.rst	2026-03-27 20:08:56.539850985 +0100
@@ -0,0 +1 @@
+Reject leading dashes in URLs passed to :func:`webbrowser.open`