Pixel phones have earned a reputation for being security-conscious, and in this blog, the authors take a look at how Pixel mitigates common exploits on cellular basebands. The cellular baseband is the processor on a device responsible for handling all cellular communication, and it is a complex software that is susceptible to bugs and errors. Security researchers have increasingly exploited this attack vector, demonstrating the possibility of exploiting basebands used in popular smartphones. Pixel has been deploying security hardening mitigations in their basebands for years, and the Pixel 9 represents the most hardened baseband they've shipped yet. The authors highlight the importance of baseband security, noting that most basebands lack exploit mitigations commonly deployed elsewhere and considered best practices in software development. The authors also note that exploit vendors and cyber-espionage firms abuse these vulnerabilities to breach the privacy of individuals without their consent. In response to the rising threat of baseband security attacks, Pixel has incrementally incorporated proactive defenses over the years, including Bounds Sanitizer, Integer Overflow Sanitizer, Stack Canaries, Control Flow Integrity, and Auto-Initialize Stack Variables. These security measures significantly increase Pixel 9's resilience to baseband attacks, demonstrating Pixel's commitment to protecting its users across the entire software stack. The authors also note that Android and Pixel have proactively updated their Vulnerability Rewards Program, placing a greater emphasis on identifying and addressing exploitable bugs in connectivity firmware.