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EmilStyrke mannequin opened this issue Mar 19, 2021 · 3 comments
Open

email: encoded headers lose their quoting when refolded #87720

EmilStyrke mannequin opened this issue Mar 19, 2021 · 3 comments
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3.9 only security fixes stdlib Python modules in the Lib dir topic-email type-bug An unexpected behavior, bug, or error

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@EmilStyrke
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EmilStyrke mannequin commented Mar 19, 2021 •
edited by bedevere-app bot
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BPO 43554
Nosy @warsaw, @bitdancer, @maxking
Files
  • test_folding_bug.py: unittest displaying the issue
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    GitHub fields:

    assignee = None
closed_at = None
created_at = <Date 2021-03-19.09:45:02.487>
labels = ['type-bug', 'library', '3.9']
title = 'email: encoded headers lose their quoting when refolded'
updated_at = <Date 2021-03-19.18:30:12.248>
user = 'https://bugs.python.org/EmilStyrke'

    bugs.python.org fields:

    activity = <Date 2021-03-19.18:30:12.248>
actor = 'shihai1991'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-03-19.09:45:02.487>
creator = 'Emil.Styrke'
dependencies = []
files = ['49893']
hgrepos = []
issue_num = 43554
keywords = []
message_count = 1.0
messages = ['389061']
nosy_count = 4.0
nosy_names = ['barry', 'r.david.murray', 'Emil.Styrke', 'maxking']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue43554'
versions = ['Python 3.9']

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    @EmilStyrke
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    EmilStyrke mannequin commented Mar 19, 2021

    When a header with an encoded (QP or Base64) display_name is refolded, it may lose (some of) its encoding. If it then contains illegal "atext" tokens, an invalid header will result.

    For example, From: =?utf-8?Q?a=2C=20123456789012345678901234567890123456?= <abc@example.com> will become From: a, 123456789012345678901234567890123456 <abc@example.com> This contains a comma character which needs to be quoted: correct rendering would be From: "a, 123456789012345678901234567890123456" <abc@example.com>. Note that this example isn't even folded to multiple lines, since the decoded text is short enough to fit in one line.

    This can be triggered by BytesParser(policy=policy.default).parsebytes("From: =?utf-8?Q?a=2C=20123456789012345678901234567890123456?= <abc@example.com>").as_bytes(), but the offending code seems to be in or below email.policy.EmailPolicy.fold. See attached file for examples with and without folding.

    @EmilStyrke EmilStyrke mannequin added 3.9 only security fixes stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error labels Mar 19, 2021
    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
    @brychcy
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    brychcy commented May 12, 2025

    See #121284

    @bedevere-app bedevere-app bot mentioned this issue May 19, 2025
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    @medmunds
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    rfc2047 RFC-2047 encoded-word

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