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gh-152248: Fix zoneinfo TZ string regex to only accept ASCII letters #152510

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gh-152248: Fix zoneinfo TZ string regex to only accept ASCII letters #152510

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gh-152248: Fix zoneinfo TZ string regex to only accept ASCII letters 
The pure-Python _parse_tz_str regex used [^<0-9:.+-]+ for unquoted
abbreviations, which matched whitespace and non-ASCII characters.
The C implementation only accepts ASCII letters. Tighten the regex
to [a-zA-Z]+ to match C behavior.
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@factnn
factnn committed Jun 28, 2026
commit 00825d070cae6a58bb5354ca98409e81b28478b0
5 changes: 5 additions & 0 deletions Lib/test/test_zoneinfo/test_zoneinfo.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1222,6 +1222,11 @@ def test_invalid_tzstr(self):
"AAA4BBB,J60/2:00:100,J300/2",
"AAA4BBB,J60/2,J300/2:00:0",
"AAA4BBB,J60/2,J300/2:00:100",
# gh-152248: unquoted abbreviation must be ASCII letters only
"A A4BBB,J60/2,J300/2", # space in std abbreviation
"AAA4B B,J60/2,J300/2", # space in dst abbreviation
"ÄAA4BBB,J60/2,J300/2", # non-ASCII letter in std
"AAA4ÄBB,J60/2,J300/2", # non-ASCII letter in dst
]

for invalid_tzstr in invalid_tzstrs:
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4 changes: 2 additions & 2 deletions Lib/zoneinfo/_zoneinfo.py
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Original file line number Diff line number Diff line change
Expand Up @@ -640,11 +640,11 @@ def _parse_tz_str(tz_str):

parser_re = re.compile(
r"""
(?P<std>[^<0-9:.+-]+|<[a-zA-Z0-9+-]+>)
(?P<std>[a-zA-Z]+|<[a-zA-Z0-9+-]+>)
(?:
(?P<stdoff>[+-]?\d{1,3}(?::\d{2}(?::\d{2})?)?)
(?:
(?P<dst>[^0-9:.+-]+|<[a-zA-Z0-9+-]+>)
(?P<dst>[a-zA-Z]+|<[a-zA-Z0-9+-]+>)
(?P<dstoff>[+-]?\d{1,3}(?::\d{2}(?::\d{2})?)?)?
)? # dst
)? # stdoff
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2026-06-29-00-00-01.gh-issue-152248.XxYyZz.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Fix the pure-Python :func:`zoneinfo._parse_tz_str` to reject unquoted
POSIX TZ string abbreviations containing non-ASCII characters or
whitespace, matching the C implementation's behavior.
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