The nsTransformedTextRun::SetCapitalization function in Mozilla Firefox before 36.0 allows remote attackers to execute arbitrary code or cause a denial of service (out-of-bounds read of heap memory) via a crafted Cascading Style Sheets (CSS) token sequence that triggers a restyle or reflow operation.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.