platform/msm_shared/mmc.c in the Qualcomm components in Android before 2016-07-05 on Nexus 7 (2013) devices mishandles the power-on write-protect feature, which allows attackers to gain privileges via a crafted application, aka Android internal bug 28821253 and Qualcomm internal bug CR580567.
Software security is not security software. Here we're concerned with topics like authentication, access control, confidentiality, cryptography, and privilege management.