Stagefright refers to the libstagefright media library in Android. The flaw was found by Zimperium vice-president for platform research and exploitation, Joshua Drake.
According to an analysis at eWeek, the Stagefright issues were to do with integer overflows that led to memory buffer overflows that were potentially exploitable.
Google has issued patches for 115 media server-related flaws, with 49 being found in libstagefright itself, 35 in libmedia, and 31 in libraries which are dependencies for libstagefright.
While Google has said it will make improvements in its next release, Android-N, to isolate the media server issues, the changes are unlikely to be back-ported to earlier Android versions.
The discovery of Stagefright was what led to Google's deciding to issue monthly security updates for Android.
However, the updates have done little to reduce security issues in the Android sphere as few companies which make Android devices bother to collate and issue the patches to their userbase.