Apple recently patched a critical vulnerability in iOS, the operating system that runs all iPhones. Now it appears that the same flaw may affect all Macs running OS X as well. So far there is no official confirmation from Apple, but security experts are warning Mac users to avoid using public networks until we know more.
Update 2014Feb24: Apple released a patch for iOS that fixes this flaw on iPhones. Meanwhile, it looks like the flaw does affect Macs (OS X). A security researcher at ImperialViolet has created a proof-of-concept test page (no longer functional). Steer your Mac web browser to that page; if you get an error message, your browser is not affected by the flaw. Vulnerable Mac browsers will see a message to that effect. Tests on my own Mac show Safari as vulnerable, while Firefox is not.
Update 2014Feb25: TechDirt has an amusing article on the surprising lack of information coming from Apple. There’s a general sense of dissatisfaction with Apple, and increasing clamour for information – any information – on how this issue affects Macs.
Update 2014Feb26: Apple has released an update for OS X that addresses this issue. OS X 10.9.2 includes several other security fixes and bug fixes.