Secunia

Some vulnerabilities have been reported in Mailman, which can be exploited by malicious people to conduct cross-site scripting and phishing attacks, and cause a DoS (Denial of Service).

1) An error in the logging functionality can be exploited to inject a spoofed log message into the error log via a specially crafted URL containing newline characters.

Successful exploitation may trick an administrator into visiting a malicious web site.

2) An error in the processing of malformed headers which does not follow the RFC 2231 standard can be exploited to cause a DoS (Denial of Service).

3) Some input isn't properly sanitised before being returned to the user. This can be exploited to execute arbitrary HTML and script code in a user's browser session in context of an affected site.

Examples:
http://[host]/mailman/admin/mailman/members?findmember=[code]
http://[host]/mailman/edithtml/tests/listinfo.html?html_code=[code]

The vulnerabilities have been reported in versions 2.1.0 through 2.1.8. Prior versions may also be affected.

A format string error has also been reported.

Solution
Update to version 2.1.9.
Further details available in Customer Area

Provided and/or discovered by
1, 3) Moritz Naumann
2) Reported by the vendor.

The vendor also credits Karl Chen for reporting the format string error.

Changelog
Further details available in Customer Area

Original Advisory
Moritz Naumann:
http://moritz-naumann.com/adv/0013/mailmanmulti/0013.txt

Deep Links
Links available in Customer Area