Jon Oberheide has reported two vulnerabilities in CoSign, which can be exploited by malicious users to hijack other user sessions and by malicious people to bypass certain security restrictions.

Certain input passed via POST requests are not properly sanitised before being used by the daemon. These can be exploited to insert certain commands via carriage return sequences in the cookie or data of a POST request.

Successful exploitation e.g. allows a non-authenticated user to bypass the authentication mechanism and an authenticated user to assume the identity of other users.

The vulnerabilities are reported in versions 2.0.1 and 2.0.2. Other versions may also be affected.

Solution
Apply patch or update to version 2.0.2a or 1.9.4b.
Further details available to Secunia VIM customers

Provided and/or discovered by
Jon Oberheide, University of Michigan

Changelog
Further details available to Secunia VIM customers

Original Advisory
http://www.umich.edu/~umweb/software/cosign/cosign-vuln-2007-001.txt
http://www.umich.edu/~umweb/software/cosign/cosign-vuln-2007-002.txt

Deep Links
Links available to Secunia VIM customers