Mono is an open source implementation of Microsoft’s .NET Framework.
Mono does not properly randomize hash functions for form posts to protect against hash collision attacks.
A remote attacker could send specially crafted parameters, possibly resulting in a Denial of Service condition.
There is no known workaround at this time.
All Mono users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=dev-lang/mono-2.10.9-r2"