From 44f1cc679123978895a21b424ab9678bf86b4c78 Mon Sep 17 00:00:00 2001 From: Seth Michael Larson 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 ++++++++++++++ .../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 diff --git a/Lib/test/test_webbrowser.py b/Lib/test/test_webbrowser.py index 9d608d63a01ed3..0ac985f56c840e 100644 --- a/Lib/test/test_webbrowser.py +++ b/Lib/test/test_webbrowser.py @@ -59,6 +59,11 @@ def test_open(self): 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): diff --git a/Lib/webbrowser.py b/Lib/webbrowser.py index 5d72524c087677..0fd0aeb3c1b6ef 100755 --- a/Lib/webbrowser.py +++ b/Lib/webbrowser.py @@ -155,6 +155,12 @@ def open_new(self, url): 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 @@ -172,6 +178,7 @@ def __init__(self, name): 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: @@ -192,6 +199,7 @@ def open(self, url, new=0, autoraise=True): 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) @@ -257,6 +265,7 @@ def _invoke(self, args, remote, autoraise, url=None): 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: @@ -358,6 +367,7 @@ class Konqueror(BaseBrowser): 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" @@ -442,6 +452,7 @@ def _remote(self, action): 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: @@ -605,6 +616,7 @@ def register_standard_browsers(): 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: @@ -637,6 +649,7 @@ def __init__(self, name): 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: @@ -689,6 +702,7 @@ def _name(self, val): 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: diff --git a/Misc/NEWS.d/next/Security/2026-01-16-12-04-49.gh-issue-143930.zYC5x3.rst b/Misc/NEWS.d/next/Security/2026-01-16-12-04-49.gh-issue-143930.zYC5x3.rst new file mode 100644 index 00000000000000..0f27eae99a0dfd --- /dev/null +++ b/Misc/NEWS.d/next/Security/2026-01-16-12-04-49.gh-issue-143930.zYC5x3.rst @@ -0,0 +1 @@ +Reject leading dashes in URLs passed to :func:`webbrowser.open`