Tavis Ormandy has reported a vulnerability in libpng, which can be exploited by malicious people to cause a Denial of Service, disclose potentially sensitive information, or potentially compromise an application using the library. The vulnerability is caused due to the improper handling of PNG chunks unknown to the library. This can be exploited to trigger the use of uninitialized memory in e.g. a free() call via unknown PNG chunks having a length of zero. Successful exploitation may allow execution of arbitrary code, but requires that the application calls the png_set_read_user_chunk_fn() function or the png_set_keep_unknown_chunks() function under specific conditions.