PJSIP is a free and open source multimedia communication library written in C with high level API in C, C++, Java, C#, and Python languages. SRTP is a higher level media transport which is stacked upon a lower level media transport such as UDP and ICE. Currently a higher level transport is not synchronized with its lower level transport that may introduce use-after-free issue. This vulnerability affects applications that have SRTP capability ("PJMEDIA_HAS_SRTP" is set) and use underlying media transport other than UDP. This vulnerability’s impact may range from unexpected application termination to control flow hijack/memory corruption. The patch is available as a commit in the master branch.