CVE 2006-2447, in which Radoslaw Zielinski spotted a nasty in spamd’s ‘vpopmail’ support in pretty much all recent versions of Apache SpamAssassin.
If you use spamd with vpopmail, go read the advisory and determine if you need to take action. Not many people will need to, I think; it’s a very rare setup. Still, it’s important to get the warning out there anyway.
The irony is that the bug is triggered partly by the “–paranoid” switch. This was intended to increase security, by increasing paranoia when possibly-unsafe situations arose — hence providing a great demonstration of how the addition of optional code paths, even in the best intentions, can reduce security by allowing bugs to creep in unnoticed.