Samsung has started pushing out an update for the Exynos security issue for users in the UK. You might remember, there is a critical "bug" in the Exynos 4210 and 4412 powered Samsung phones including the world versions of the Galaxy S3 and other models. This bug allows any application to read the devices RAM, leading to all sorts of potential mischief.
A third party patch was quickly made available by Supercurio that fixed the issues, and Samsung told us they would be addressing the situation as quickly as possible. For folks in the UK using a Galaxy S3, it appears that means right now.
The update is 4.1.2 (build JZO54K) and was signed off on December 22. It's available as an over the air update, and is currently rolling out. Remember, you need to be running all stock software to accept and install any OTA updates, this one included.
There's also some speculation that this update will fix the seemingly random issue of hardware failure in the Galaxy S3 main boards, but I think it's a bit too early to suggest this. The fix to the Exynos exploit, however, is included in this update. No word on when to expect updates for other areas where folks are still in need of this critical patch, or other phones that need this update.