Race condition in the AsyncPaintWaitEvent::AsyncPaintWaitEvent function in Mozilla Firefox before 37.0.2 allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free) via a crafted plugin that does not properly complete initialization.
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.