New submission from Andrew Donnellan:
Parsing an email containing a multipart Content-Type, along with a
Content-Transfer-Encoding containing an invalid (non-ASCII-decodable) byte will
fail.
email.feedparser.FeedParser._parsegen() calls
"self._cur.get('content-transfer-encoding', '8bit')" to get the header.
It then tries to check whether the C-T-E is in the allowable set of ('7bit',
'8bit', 'binary'), and to do so case-insensitively, it tries to convert the
header to lowercase. However, because there's an invalid character in there,
it's dealing with a Header object rather than a str. Hence it throws an
AttributeError.
Correct behaviour would be to convert the Header to a str, see that it's not
valid, and continue on to handle the defect as usual.
Thanks to Daniel Axtens for finding this bug as he was running the AFL fuzzer
on the email parsing code in Patchwork
(https://github.com/getpatchwork/patchwork).
Pull request incoming.
----------
components: Library (Lib), email
files: testprog.py
messages: 297584
nosy: Andrew Donnellan, barry, r.david.murray
priority: normal
severity: normal
status: open
title: AttributeError when parsing multipart email with invalid non-decodable
Content-Transfer-Encoding
type: behavior
versions: Python 3.3, Python 3.4, Python 3.5, Python 3.6, Python 3.7
Added file: http://bugs.python.org/file46989/testprog.py
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<http://bugs.python.org/issue30835>
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