When Spectre and Meltdown were discovered, the whole industry got on its legs and started to question CPU security more seriously. There are a plethora of attacks that exploit the CPU function called branch prediction, which predicts paths of code execution so it can ready them and execute them faster. This approach is one part of the microarchitectural techniques used to add performance to the CPU design. However, nothing comes without a cost. Despite adding more performance, the branch prediction had taken a toll on the security of CPUs, making them vulnerable to side-channel attacks. Spectre and Meltdown where both discovered in 2018 and they impact millions of CPUs around the world.

Today, a new side-channel vulnerability was discovered, and on Arm CPUs. Called the Straight-Line Speculation (SLS), the speculation bug is haunting all of Arm Armv-A based processors only. This represents a wide range of devices being powered by these CPUs, so Arm is taking action to prevent it. The way SLS works is that whenever there is a change in instruction flow, the CPU just starts processing instructions found linearly in memory, instead of changing the path of flow. This action is resulting in a new SLS vulnerability marked as CVE-2020-13844. The vulnerability was discovered by Google SafeSide project last year and they have reported it to Arm. In the meantime, Arm was working on a fix and they already send them upstream to important operating systems and firmware suppliers so it can be resolved. Arm says that the chances of this attack are low, however, they can not be dismissed.