Libav Null Pointer Dereference Vulnerability in MPEG File Parser

A null pointer dereference vulnerability has been identified in Libav versions through 12.3, specifically within the MPEG file parser component. The issue arises in the 'ff_seek_frame_binary' function located in 'libavformat/utils.c'. When the parser processes malformed MPEG files, it can lead to a segmentation fault by accessing a null 'index_entries' array. This vulnerability can be exploited locally, and a proof-of-concept exploit is publicly available.

Impact

Exploitation of this vulnerability causes a segmentation fault, leading to a crash of the application.

Reproduction

The vulnerability can be reproduced using 'avconv', a Libav command-line tool. After compiling Libav with specific flags to disable shared libraries and inline assembly, the tool can be run with the '-ss' option to seek a specific timestamp in a malformed MPEG file. This file, which is available as part of the VulDB entry, triggers the null pointer dereference when processed, causing 'avconv' to crash.