[SECURITY] Disable outbound and file access for reportlab (CVE-2026-57535)

src/pretix/helpers/apps.py

@@ -29,3 +29,8 @@ class PretixHelpersConfig(AppConfig):
     def ready(self):
         from .monkeypatching import monkeypatch_all_at_ready
         monkeypatch_all_at_ready()
+
+        # Ensure reportlab does not make any calls to the internet
+        from reportlab import rl_config
+        rl_config.trustedHosts = []
+        rl_config.trustedSchemes = ['data']

src/tests/helpers/test_reportlab.py

@@ -0,0 +1,52 @@
+#
+# This file is part of pretix (Community Edition).
+#
+# Copyright (C) 2014-2020  Raphael Michel and contributors
+# Copyright (C) 2020-today pretix GmbH and contributors
+#
+# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
+# Public License as published by the Free Software Foundation in version 3 of the License.
+#
+# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
+# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
+# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
+# this file, see <https://pretix.eu/about/en/license>.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
+# <https://www.gnu.org/licenses/>.
+#
+import pytest
+from reportlab.platypus import Paragraph
+
+
+def test_http_access_disabled(monkeypatch):
+    def guard(*args, **kwargs):
+        pytest.fail("No internet wanted!")
+
+    monkeypatch.setattr('socket.socket', guard)
+
+    with pytest.raises(OSError, match="Cannot open resource"):
+        Paragraph(
+            '<img src="https://static.pretix.cloud/static/pretixeu/img/opengraph.png"/>',
+        )
+
+
+def test_file_access_disabled_scheme(monkeypatch):
+    with pytest.raises(OSError, match="Cannot open resource"):
+        Paragraph(
+            '<img src="file:///etc/passwd" />',
+        )
+
+
+@pytest.mark.xfail
+def test_file_access_disabled_direct(monkeypatch):
+    # Unfortunately this is not prevented by the reprotlab config, but the risk is low since only valid images
+    # can be used.
+    with pytest.raises(OSError, match="Cannot open resource"):
+        Paragraph(
+            '<img src="/etc/passwd" />',
+        )