We examine the lifetime of API vulnerabilities on Android and propose an exponential decay model of the uptake of updates after the release of a fix. We apply our model to a case study of the JavaScript-to-Java interface vulnerability. This vulnerability allows untrusted JavaScript in a WebView to break out of the JavaScript sandbox allowing remote code execution on Android phones, this can often then be further exploited to gain root access. While this vulnerability was first reported in 2012-12-21 we predict that the fix will not have been deployed to 95% of devices until 2018-01-10, 5.2 years after the release of the fix. We show how this vulnerability is exploitable in many apps and the role that ad-libraries have in making this flaw so widespread.