Core Lightning v26.04.1 is a hotfix update addressing critical issues in build and protocol correctness identified shortly after the v26.04 release. Key fixes include the rejection of malformed channel_announcement messages to prevent gossip store corruption, adjustments to printf format specifiers for improved compatibility across different platforms, and removal of __int128 usage to restore builds on 32-bit targets. This release ensures compliance with the BOLT specification and enhances the stability of the Lightning Network implementation.