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.
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Pjsip | Teluu | * | 2.13.1 (including) |
| Asterisk | Ubuntu | bionic | * |
| Asterisk | Ubuntu | lunar | * |
| Asterisk | Ubuntu | mantic | * |
| Asterisk | Ubuntu | trusty | * |
| Asterisk | Ubuntu | xenial | * |
| Ring | Ubuntu | bionic | * |
| Ring | Ubuntu | lunar | * |
| Ring | Ubuntu | mantic | * |
| Ring | Ubuntu | trusty | * |
| Ring | Ubuntu | xenial | * |
The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:
In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.