(RHSA-2005:550) openssh security update

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

A bug was found in the way the OpenSSH server handled the MaxStartups and
LoginGraceTime configuration variables. A malicious user could connect to
the SSH daemon in such a way that it would prevent additional logins from
occuring until the malicious connections are closed. The Common
Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name
CAN-2004-2069 to this issue.

Additionally, the following issues are resolved with this update:

• The -q option of the ssh client did not suppress the banner message sent
  by the server, which caused errors when used in scripts.

• The sshd daemon failed to close the client connection if multiple X
  clients were forwarded over the connection and the client session exited.

• The sftp client leaked memory if used for extended periods.

• The sshd daemon called the PAM functions incorrectly if the user was
  unknown on the system.

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