GStreamer is a library for constructing graphs of media-handling components. An Use-After-Free read vulnerability has been discovered affecting the processing of CodecPrivate elements in Matroska streams. In the GST_MATROSKA_ID_CODECPRIVATE case within the gst_matroska_demux_parse_stream function, a data chunk is allocated using gst_ebml_read_binary. Later, the allocated memory is freed in the gst_matroska_track_free function, by the call to g_free (track->codec_priv). Finally, the freed memory is accessed in the caps_serialize function through gst_value_serialize_buffer. The freed memory will be accessed in the gst_value_serialize_buffer function. This results in a UAF read vulnerability, as the function tries to process memory that has already been freed. This vulnerability is fixed in 1.24.10.
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 |
|---|---|---|---|
| Gstreamer | Gstreamer_project | * | 1.24.10 (excluding) |
| Gst-plugins-good1.0 | Ubuntu | focal | * |
| Gst-plugins-good1.0 | Ubuntu | jammy | * |
| Gst-plugins-good1.0 | Ubuntu | noble | * |
| Gst-plugins-good1.0 | Ubuntu | oracular | * |
| Gst-plugins-good1.0 | Ubuntu | upstream | * |
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.