PJSIP is a free and open source multimedia communication library written in C language implementing standard based protocols such as SIP, SDP, RTP, STUN, TURN, and ICE. In versions up to and including 2.11.1 when in a dialog set (or forking) scenario, a hash key shared by multiple UAC dialogs can potentially be prematurely freed when one of the dialogs is destroyed . The issue may cause a dialog set to be registered in the hash table multiple times (with different hash keys) leading to undefined behavior such as dialog list collision which eventually leading to endless loop. A patch is available in commit db3235953baa56d2fb0e276ca510fefca751643f which will be included in the next release. There are no known workarounds for this issue.
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 | * | 2.11.1 (including) |
| Asterisk | Ubuntu | bionic | * |
| Asterisk | Ubuntu | impish | * |
| Asterisk | Ubuntu | kinetic | * |
| Asterisk | Ubuntu | lunar | * |
| Asterisk | Ubuntu | mantic | * |
| Asterisk | Ubuntu | trusty | * |
| Asterisk | Ubuntu | xenial | * |
| Pjproject | Ubuntu | bionic | * |
| Pjproject | Ubuntu | trusty | * |
| Pjproject | Ubuntu | xenial | * |
| Ring | Ubuntu | bionic | * |
| Ring | Ubuntu | esm-apps/bionic | * |
| Ring | Ubuntu | focal | * |
| Ring | Ubuntu | impish | * |
| 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.