OpenSSH: Multiple Denial of Service vulnerabilities
Gentoo Linux Security Advisory
||GLSA 200611-06 / openssh
||November 13, 2006
||November 13, 2006: 01
All supported architectures
Several Denial of Service vulnerabilities have been identified in OpenSSH.
OpenSSH is a complete SSH protocol version 1.3, 1.5 and 2.0
implementation and includes sftp client and server support.
Tavis Ormandy of the Google Security Team has discovered a
pre-authentication vulnerability, causing sshd to spin until the login
grace time has been expired. Mark Dowd found an unsafe signal handler
that was vulnerable to a race condition. It has also been discovered
that when GSSAPI authentication is enabled, GSSAPI will in certain
cases incorrectly abort.
The pre-authentication and signal handler vulnerabilities can cause a
Denial of Service in OpenSSH. The vulnerability in the GSSAPI
authentication abort could be used to determine the validity of
usernames on some platforms.
There is no known workaround at this time.
All OpenSSH users should upgrade to the latest version:
Code Listing 3.1: Resolution
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-misc/openssh-4.4_p1-r5"