AOH :: HP Unsorted C :: TB10351.HTM

Cosign SSO Authentication Bypass
Cosign SSO Authentication Bypass
Cosign SSO Authentication Bypass

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Author: Jon Oberheide  
Date:    Wed, April 11th, 2007

Application:              Cosign Single Sign-On
Affected Versions:        2.0.1 and previous
Vendor Website: 
Type of Vulnerability:    Authentication Bypass - Remote

cosign is a web single-sign-on system.  Written at the University of
Michigan, cosign is an open source software project and a part of the
National Science Foundation Middleware Initiative (NMI) EDIT software
release.  cosign is deployed extensively at the University of Michigan
and at educational institutions and other organizations around the

Two critical remote vulnerabilities exist within the CGI component of
cosign allowing authentication bypass and impersonation of an arbitrary
user.  The full details of each vulnerability can be found at the
following links: 

Organizations utilizing cosign should upgrade to versions 1.9.4b or
2.0.2a available at 

Jon Oberheide  
GnuPG Key: 1024D/F47C17FE
Fingerprint: B716 DA66 8173 6EDD 28F6  F184 5842 1C89 F47C 17FE

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