https://github.com/python/cpython/commit/670b4ac596999d207480350cf4c01e3f49a92eab
commit: 670b4ac596999d207480350cf4c01e3f49a92eab
branch: 3.13
author: tonghuaroot (童话) <[email protected]>
committer: StanFromIreland <[email protected]>
date: 2026-07-08T12:37:46+02:00
summary:
[3.13] gh-152157: Reject empty fractions in
`_datetime.{date}time.fromisoformat` (GH-152161) (#152766)
(cherry picked from commit 112c69a0514902af2d2f7d0503de6690ca59a10f)
Co-authored-by: Stan Ulbrych <[email protected]>
files:
A Misc/NEWS.d/next/Library/2026-06-25-07-08-17.gh-issue-152157.dt5Ef0.rst
M Lib/test/datetimetester.py
M Modules/_datetimemodule.c
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 4c5d03700e15b0..c0f2400456ff62 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -3396,6 +3396,10 @@ def test_fromisoformat_fails_datetime(self):
'2009-04-19T12:30:45.400 ', # Trailing space (gh-130959)
'2009-04-19T12:30:45. 400', # Space before fraction
(gh-130959)
'2020-2020', # Ambiguous 9-char date portion
+ '2009-04-19T12:30:45.+05:00', # Empty fraction before offset
+ '2009-04-19T12:30:45.-05:00', # Empty fraction before offset
+ '2009-04-19T12:30:45.Z', # Empty fraction before Z
+ '2009-04-19T12:30:45,+05:00', # Empty fraction (comma) before
offset
]
for bad_str in bad_strs:
@@ -4509,6 +4513,10 @@ def test_fromisoformat_fails(self):
'12:30:45.400 +02:30', # Space between ms and timezone
(gh-130959)
'12:30:45.400 ', # Trailing space (gh-130959)
'12:30:45. 400', # Space before fraction (gh-130959)
+ '12:30:45.+05:00', # Empty fraction before offset
+ '12:30:45.-05:00', # Empty fraction before offset
+ '12:30:45.Z', # Empty fraction before Z
+ '12:30:45,+05:00', # Empty fraction (comma) before offset
]
for bad_str in bad_strs:
diff --git
a/Misc/NEWS.d/next/Library/2026-06-25-07-08-17.gh-issue-152157.dt5Ef0.rst
b/Misc/NEWS.d/next/Library/2026-06-25-07-08-17.gh-issue-152157.dt5Ef0.rst
new file mode 100644
index 00000000000000..00e83b4af6be7a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-06-25-07-08-17.gh-issue-152157.dt5Ef0.rst
@@ -0,0 +1,3 @@
+The C implementations of :meth:`~datetime.datetime.fromisoformat` and
:meth:`~datetime.time.fromisoformat`
+now reject a decimal separator that is not followed by any
+fractional digit before a timezone designator.
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index e0d1f57c259c42..f54ec606888f88 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -1013,17 +1013,22 @@ parse_hh_mm_ss_ff(const char *tstr, const char
*tstr_end, int *hour,
has_separator = (c == ':');
}
- if (p >= p_end) {
+ if (c == '.' || c == ',') {
+ if (p >= p_end) {
+ return -3; // Decimal mark not followed by any digit
+ }
+ break;
+ }
+ else if (p >= p_end) {
return c != '\0';
}
else if (has_separator && (c == ':')) {
continue;
}
- else if (c == '.' || c == ',') {
- break;
- } else if (!has_separator) {
+ else if (!has_separator) {
--p;
- } else {
+ }
+ else {
return -4; // Malformed time separator
}
}
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