[Bug 950078] Re: Segfault when using SSLv2

[Marc Deslauriers]

This issue doesn't affect any currently supported releases of Ubuntu as
it is fixed in Ubuntu 12.04 LTS and above. Closing bug.

** Changed in: pyopenssl (Ubuntu)
       Status: Confirmed => Fix Released

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Title:
  Segfault when using SSLv2

Status in pyopenssl package in Ubuntu:
  Fix Released

Bug description:
  Attempting to construct an SSL_CTX using SSLv2_METHOD triggers a
  segfault.

  This can be reproduced most easily using the Python bindings to
  OpenSSL, provided by the python-openssl package:

  python -c '
  from OpenSSL.SSL import SSLv2_METHOD, Context

  Context(SSLv2_METHOD)
  '

  I've verified that this is a crash in OpenSSL, not in the Python
  bindings.  I use the Python bindings here because the equivalent C
  example is a lot more typing.

  This appears to affect at least Ubuntu 11.04, but not Ubuntu 11.10.
  It seems likely that the problem was introduced by whatever change was
  used to disable SSLv2 support.  However, the change should have:

   - Defined OPENSSL_NO_SSL2, which is how applications using libssl can tell if SSLv2 is supported or not.
   - Caused use of SSL_CTX_new(SSLv2_METHOD) to fail by returning NULL and setting some error state, not crash with a segfault.

  Marking this as a security bug because it's often possible to turn a
  segfault into an exploitable vulnerability.

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