updated 10:45 am EDT, Mon August 1, 2011
Issue linked to Mac OS X 10.6.8
The Snow Leopard version of Safari is failing to block cookies properly, says security firm Sophos. Users running the browser on Mac OS X 10.6.8 in particular are reportedly seeing the software continue to keep some cookies active, even when settings have been changed to block all of them. Even the Safari 5.1 update hasn't solved the problem, according to Sophos.
The issue appears to be connected to Snow Leopard rather than Safari, since Safari 5.0.5 on Mac OS X 10.6.7 manages cookies as intended. Sophos adds that there appears to be no obvious reason why some cookies are tracked in v10.6.8 and not others. The firm notes that during testing, it encountered an assortment of session, short-term and long-term cookies.
Tracking is also managed correctly in OS X Lion, which comes with Safari 5.1. Apple has not commented publicly on the topic, even on its support forums. It's therefore unknown if or when Apple will issue a patch, although the company will likely make it a Security Update for Snow Leopard rather than a v10.6.9 distribution.