User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the support for embedding various file types within the RIFF-based Director file format. Several of the asset modules distributed with Shockwave do not properly extract string values from within embedded media objects. The code attempts to null-terminate such strings using a 32-bit size value specified prior to the string value. By crafting an embedded media object with a large string size an attacker can write a NULL byte to a controlled offset from the buffer containing the string. This can be leveraged to execute arbitrary code under the context of the user running the browser.