Microsoft discovered a vulnerability pattern in multiple popular Android applications that could enable a malicious application to overwrite files in the vulnerable application’s internal data storage directory, which could lead to arbitrary code execution and token theft, among other impacts. We have shared our findings with Google’s Android Application Security Research team, as well as the developers of apps found vulnerable to this issue. We anticipate that the vulnerability pattern could be found in other applications. We’re sharing this research more broadly so developers and publishers can check their apps for similar issues, fix as appropriate, and prevent them from being introduced into new apps or releases.