https://github.com/python/cpython/commit/5858e42c539dac8394636a6e9b30472b8994851f
commit: 5858e42c539dac8394636a6e9b30472b8994851f
branch: main
author: Seth Larson <[email protected]>
committer: encukou <[email protected]>
date: 2026-06-23T15:33:51+02:00
summary:
gh-143927: Normalize all line endings (CR, CRLF, and LF) in configparser
(GH-143929)
files:
A Misc/NEWS.d/next/Security/2026-01-16-11-58-19.gh-issue-143927.aviFeG.rst
M Lib/configparser.py
M Lib/test/test_configparser.py
diff --git a/Lib/configparser.py b/Lib/configparser.py
index a53ac87276445a..3c452afe8ade48 100644
--- a/Lib/configparser.py
+++ b/Lib/configparser.py
@@ -992,7 +992,9 @@ def _write_section(self, fp, section_name, section_items,
delimiter, unnamed=Fal
value = self._interpolation.before_write(self, section_name, key,
value)
if value is not None or not self._allow_no_value:
- value = delimiter + str(value).replace('\n', '\n\t')
+ # Convert all possible line-endings into '\n\t'
+ value = (delimiter + str(value).replace('\r\n', '\n')
+ .replace('\r', '\n').replace('\n', '\n\t'))
else:
value = ""
fp.write("{}{}\n".format(key, value))
diff --git a/Lib/test/test_configparser.py b/Lib/test/test_configparser.py
index 8d8dd2a2bf27fb..4783943f71a109 100644
--- a/Lib/test/test_configparser.py
+++ b/Lib/test/test_configparser.py
@@ -526,6 +526,17 @@ def test_default_case_sensitivity(self):
cf.get(self.default_section, "Foo"), "Bar",
"could not locate option, expecting case-insensitive defaults")
+ def test_crlf_normalization(self):
+ cf = self.newconfig({"key1": "a\nb","key2": "a\rb", "key3": "a\r\nb",
"key4": "a\r\nb"})
+ buf = io.StringIO()
+ cf.write(buf)
+ cf_str = buf.getvalue()
+ self.assertNotIn("\r", cf_str)
+ self.assertNotIn("\r\n", cf_str)
+ self.assertEqual(cf_str.count("\n"), 10)
+ self.assertEqual(cf_str.count("\n\t"), 4)
+ self.assertTrue(cf_str.endswith("\n\n"))
+
def test_parse_errors(self):
cf = self.newconfig()
self.parse_error(cf, configparser.ParsingError,
diff --git
a/Misc/NEWS.d/next/Security/2026-01-16-11-58-19.gh-issue-143927.aviFeG.rst
b/Misc/NEWS.d/next/Security/2026-01-16-11-58-19.gh-issue-143927.aviFeG.rst
new file mode 100644
index 00000000000000..ca554997e5c396
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2026-01-16-11-58-19.gh-issue-143927.aviFeG.rst
@@ -0,0 +1,2 @@
+Normalize all line endings (CR, CRLF, and LF) to LF+TAB when writing
+multi-line configparser values.
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