Integer Overflow or Wraparound
In opencv/modules/imgcodecs/src/grfmt_pxm.cpp, function ReadNumber did not checkout the input length, which lead to integer overflow. If the image is from remote, may lead to remote code execution or denial of service. This affects Opencv 3.3 and earlier.
CWE-190 - Integer Overflow or Wraparound
The software performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control.