Oracle recently released update 17 of Java 7 after researchers discovered multiple new vulnerabilities in the software once again. One of the vulnerabilities was found being actively exploited in the wild, which is what led to the patch. Oracle’s release notes mentioned the following:
This Security Alert addresses security issues CVE-2013-1493 (US-CERT VU#688246) and another vulnerability affecting Java running in web browsers. Due to the severity of these vulnerabilities, and the reported exploitation of CVE-2013-1493 "in the wild," Oracle strongly recommends that customers apply the updates provided by this Security Alert as soon as possible.
Apple pushed out an update on February 19th to help cope with a similar vulnerability. The latest Java update for OS X Lion and Mountain Lion weighs in at 63.48 MB, while the Snow Leopard version comes in at 69.32 MB. Both of the updates can be downloaded from Apple’s support webpage or via Software Update.