openssl - protocol design flaw

DSA-2141 consists of three individual parts, which can be viewed in the
mailing list archive:
DSA 2141-1 (openssl),
DSA 2141-2 (nss),
DSA 2141-3 (apache2), and
DSA 2141-4 (lighttpd).
This page only covers the first part, openssl.

• CVE-2009-3555
  Marsh Ray, Steve Dispensa, and Martin Rex discovered a flaw in the TLS
  and SSLv3 protocols. If an attacker could perform a man in the middle
  attack at the start of a TLS connection, the attacker could inject
  arbitrary content at the beginning of the user’s session. This update
  adds backported support for the new RFC5746 renegotiation extension
  which fixes this issue.

If openssl is used in a server application, it will by default no
longer accept renegotiation from clients that do not support the
RFC5746 secure renegotiation extension. A separate advisory will add
RFC5746 support for nss, the security library used by the iceweasel
web browser. For apache2, there will be an update which allows to
re-enable insecure renegotiation.

This version of openssl is not compatible with older versions of tor.
You have to use at least tor version 0.2.1.26-1~lenny+1, which has
been included in the point release 5.0.7 of Debian stable.

Currently we are not aware of other software with similar compatibility
problems.

• CVE-2010-4180
  In addition, this update fixes a flaw that allowed a client to bypass
  restrictions configured in the server for the used cipher suite.

For the stable distribution (lenny), this problem has been fixed
in version 0.9.8g-15+lenny11.

For the unstable distribution (sid), and the testing distribution
(squeeze), this problem has been fixed in version 0.9.8o-4.

We recommend that you upgrade your openssl package.

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://www.debian.org/security/