In the past it was by accident, but from now on it'll be by policy: Adobe will add to the  workload by releasing their patches on a quarterly schedule to concide with the Microsoft monthly scheme.

June yielded just one bulletin:

apsb09-07

Affects Acrobat (Reader) on Windows and Mac to Adobe Reader 9.1.2 and Acrobat 9.1.2. Also available are Acrobat 8.1.6 and Acrobat 7.1.3.

This fixes following CVE names:

CVE-2009-0198, CVE-2009-0509, CVE-2009-0510, CVE-2009-0511, CVE-2009-0512, CVE-2009-0888, CVE-2009-0889, CVE-2009-1855, CVE-2009-1856, CVE-2009-1857, CVE-2009-1858, CVE-2009-1859, and CVE-2009-1861.

Note that the bulletin states "Additionally, this update resolves Adobe internally discovered issues".

Among the list are a number of JBIG2 filter vulnerabilities.

JBIG2 filter vulnerabilities have been exploited in the past, so you really want this upgrade.

UPDATE:

Roseman wrote in to point out the bulletin contains: "Security updates for Adobe Reader on the UNIX platform will be available on June 16, 2009". which effectively gives the attackers time to reverse engineer the vulnerabilities from the patches for Windows and Mac and build exploits for the unix versions without those users having any chance to patch.

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Swa Frantzen -- Section 66