IOS 15.5 arrived on May 16 and brought dozens of security fixes alongside Wallet, Podcasts updates.
The only new feature introduced is improved video control when tuning in to live sports
Prior to that, iOS 15.6 arrived in July 2022. A Kernel issue described as “an application may be able to execute arbitrary code with kernel privileges,” and a WebKit issue described as “processing maliciously crafted web content may lead to arbitrary code execution.” There are two vulnerabilities addressed, according to Apple’s security content page. The most recent version of iOS 15.6.1 which patches critical flaws that may have been actively exploited. The first version of iOS 15 arrived on September 20, 2021, however Apple has issued numerous updates since.
