Adobe has issued a Security Update for Photoshop CS5 + CS5.1, after their mildly bungled announcement. PhotographyUNcapped reported on this problem 3 weeks ago in this post:
Photoshop Security Vulnerability in CS5 and Earlier Versions CS4 CS3 CS2 on Mac + Win – CS6 Upgrade Considered Safe?
At first, Adobe seemed to say that the cure for the vulnerability in CS5 was to buy CS6; a statement not taken to fondly around the net. No surprise about the poor reception. Now, Adobe has made good on the need for a CS5 update to correct the issue.
This addresses a long-standing vulnerability of Photoshop Cs5 in tif files which could be exploited by dirty-doers. However, it appears to only apply to CS5, Cs5.1, and not to the same issue with CS4, CS3, etc.
As with all updates, backup first.
Good luck, Annie