Haml is a templating engine for HTML.
It was discovered that Haml was not correctly filtering out special characters which may be used for attributes.
A remote attacker could possibly execute arbitrary code with the privileges of the process or cause a Denial of Service condition.
There is no known workaround at this time.
All Haml users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=dev-ruby/haml-5.1.2"