(RHSA-2007:0540) Moderate: openssh security and bug fix update

OpenSSH is OpenBSD’s SSH (Secure SHell) protocol implementation. These
packages include the core files necessary for both the OpenSSH client and
server.

A flaw was found in the way the ssh server wrote account names to the audit
subsystem. An attacker could inject strings containing parts of audit
messages, which could possibly mislead or confuse audit log parsing tools.
(CVE-2007-3102)

A flaw was found in the way the OpenSSH server processes GSSAPI
authentication requests. When GSSAPI authentication was enabled in the
OpenSSH server, a remote attacker was potentially able to determine if a
username is valid. (CVE-2006-5052)

The following bugs in SELinux MLS (Multi-Level Security) support has also
been fixed in this update:

• It was sometimes not possible to select a SELinux role and level when
  logging in using ssh.

• If the user obtained a non-default SELinux role or level, the role change
  was not recorded in the audit subsystem.

• In some cases, on labeled networks, sshd allowed logins from level ranges
  it should not allow.

The updated packages also contain experimental support for using private
keys stored in PKCS#11 tokens for client authentication. The support is
provided through the NSS (Network Security Services) library.

All users of openssh should upgrade to these updated packages, which
contain patches to correct these issues.