Currently, Apple's latest firmware is iOS 11.3 and developers have been seeded with iOS 11.4. iOS 11.3 brings numerous new features including ARKit 1.5, Battery Health, iPad charge management, new Animoji, Business Chat, Health Records, Music Video experience in Apple Music, review sorting in App Store, accessibility improvements, and much more. If you accidentally update or restore, you'll find yourself on iOS 11.3.
Typically, it's advised that users looking to jailbreak remain on the lowest firmware possible; however, we currently don't have any information on a jailbreak planned for iOS 11.2.6. The most recent jailbreak release works on iOS 11 - iOS 11.1.2.
Please follow iClarified on Twitter, Facebook, Google+, or RSS for updates.