[ GLSA 200611-06 ] OpenSSH: Multiple Denial of Service vulnerabilities

[GLSA]

Gentoo Linux Security Advisory

Title: OpenSSH: Multiple Denial of Service vulnerabilities (GLSA 200611-06)
Severity: normal
Exploitable: remote
Date: November 13, 2006
Bug(s): #149502
ID: 200611-06

Synopsis

Several Denial of Service vulnerabilities have been identified in OpenSSH.

Background

OpenSSH is a complete SSH protocol version 1.3, 1.5 and 2.0 implementation and includes sftp client and server support.

Affected Packages

Package: net-misc/openssh
Vulnerable: < 4.4_p1-r5
Unaffected: >= 4.4_p1-r5
Architectures: All supported architectures


Description

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.

Impact

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.

Workaround

There is no known workaround at this time.

Resolution

All OpenSSH users should upgrade to the latest version: