The (1) cf2_initLocalRegionBuffer and (2) cf2_initGlobalRegionBuffer functions in cff/cf2ft.c in FreeType before 2.5.3 do not properly check if a subroutine exists, which allows remote attackers to cause a denial of service (assertion failure), as demonstrated by a crafted ttf file.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.