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[3.10] gh-143935: Email preserve parens when folding comments (GH-143936) - #144350

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Mar 2, 2026
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[3.10] gh-143935: Email preserve parens when folding comments (GH-143936)#144350
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@edgarrmondragonedgarrmondragon commented Jan 30, 2026

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Fix a bug in the folding of comments when flattening an email message using a modern email policy. Comments consisting of a very long sequence of non-foldable characters could trigger a forced line wrap that omitted the required leading space on the continuation line, causing the remainder of the comment to be interpreted as a new header field. This enabled header injection with carefully crafted inputs.
(cherry picked from commit 17d1490)

Co-authored-by: Seth Michael Larson seth@python.org
Co-authored-by: Denis Ledoux dle@odoo.com

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would you mind taking a look @sethmlarson?

…ythonGH-143936)
Fix a bug in the folding of comments when flattening an email message
using a modern email policy. Comments consisting of a very long sequence of
non-foldable characters could trigger a forced line wrap that omitted the
required leading space on the continuation line, causing the remainder of
the comment to be interpreted as a new header field. This enabled header
injection with carefully crafted inputs.
(cherry picked from commit 17d1490)
Co-authored-by: Seth Michael Larson seth@python.org
Co-authored-by: Denis Ledoux dle@odoo.com
- Issue: Fix folding of long comments of unfoldable characters in email headers python#143935
Signed-off-by: Edgar Ramírez Mondragón <edgarrm358@gmail.com>
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pablogsal merged commit 003b831 into python:3.10Mar 2, 2026
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edgarrmondragon deleted the backport-17d1490-3.10 branch March 3, 2026 00:29
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@edgarrmondragon@pablogsal@sethmlarson