cpython/Misc/NEWS.d/next/Library/2019-05-27-15-29-46.bpo-30835.3FoaWH.rst
Abhilash Raj aa79707262 bpo-30835: email: Fix AttributeError when parsing invalid CTE (GH-13598)
* bpo-30835: email: Fix AttributeError when parsing invalid Content-Transfer-Encoding

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() gets the header and
attempts to convert it to lowercase before comparing it with the accepted
encodings, but as the header contains an invalid byte, it's returned as a
Header object rather than a str.

Cast the Content-Transfer-Encoding header to a str to avoid this.

Found using the AFL fuzzer.

Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Andrew Donnellan <andrew@donnellan.id.au>

* Add email and NEWS entry for the bugfix.
2019-06-04 11:00:47 -07:00

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Fixed a bug in email parsing where a message with invalid bytes in
content-transfer-encoding of a multipart message can cause an AttributeError.
Patch by Andrew Donnellan.