ZPublisher.HTTPRequest._scrubHeader in Zope 2 before 2.13.19, as used in Plone before 4.3 beta 1, allows remote attackers to inject arbitrary HTTP headers via a linefeed (LF) character.
https://plone.org/products/plone/security/advisories/20121106/02
https://plone.org/products/plone-hotfix/releases/20121106
https://bugs.launchpad.net/zope2/+bug/930812