system
Describe <CVE-2011-3937>.
user
What is <CVE-2011-3937>?
assistant
The H.263 codec (libavcodec/h263dec.c) in FFmpeg 0.7.x before 0.7.12, 0.8.x before 0.8.11, and unspecified versions before 0.10, and in Libav 0.5.x before 0.5.9, 0.6.x before 0.6.6, 0.7.x before 0.7.5, and 0.8.x before 0.8.1 has unspecified impact and attack vectors related to "width/height changing with frame threads.".