OnePlus 6 has started receiving OxygenOS 5.1.8 as a new software update. Specifically for Indian users, the update brings all the features that debuted through the OxygenOS 5.1.7 released last week. This means that among other changes, the update patches the bootloader vulnerability for OnePlus 6 users in India. Also, it includes fresh optimisations to enhance call quality and fixes a bunch of system stability issues. OnePlus notably decided to skip the previous OxygenOS rollout for Indian users to fix the stability issues reported in OxygenOS 5.1.6 and release OxygenOS 5.1.8 as the next over-the-air (OTA) update.
According to the changelog posted on the OnePlus forums, the OxygenOS 5.1.8 update for the OnePlus 6 optimises call quality and fixes system stability issues. The update also improves network stability and general bug fixes. While the new update is available for OnePlus 6 users worldwide, it brings the features of the OxygenOS 5.1.7 for Indian users as they didn't receive the previous update due to some stability issues reported after installing OxygenOS 5.1.6.
Therefore, OnePlus 6 users in India receive a fix for the scheduled setting issue spotted on the Do Not Disturb (DND) mode as well as an updated bootloader that patches the vulnerability that was allowing attackers to bypass bootloader protection measures and boot a modified firmware image. There are also general bug fixes and improvements that all are a part of last week's OxygenOS 5.1.7 rollout.
Being an incremental update - just like the previous versions, the OxygenOS 5.1.8 will initially reach a small batch of users, though it will get a broader rollout in a few days. You can manually check its availability by going to Settings > System updates.