Jelle Zijlstra

When tarfile or zipfile command line interface (CLI) is used to decompress an archive, a Python script shadowing the stdlib can be created. Then if an error occurs during decompressing the next file, the newly created Python script is executed. This is especially true if the created Python is called traceback.py. The problem is that Python adds the current directory to sys.path when python -m MODULE is run, and the archive is also decompressed in the current directory. The fix removes sys.path[0] in gzip, tarfile and zipfile command line interface to prevent shadowing standard library modules from extracted files.

IMAP4.starttls() wraps the socket in TLS but leaves self. readbuf, imaplib's own read-ahead buffer, untouched. Any plaintext bytes that arrived in the same recv() as the tagged OK to STARTTLS are returned by readline() after the handshake, so the client treats them as the first responses on the protected channel. A network attacker who cannot break TLS can append forged lines after the server's OK, let the handshake complete with the real server and a valid certificate, and have the client accept the forged CAPABILITY and the forged tagged completion of the next command. This is the STARTTLS command/response injection class of CVE-2011-0411.