Multiple integer overflows in the calendar extension in PHP through 5.6.7 allow remote attackers to cause a denial of service or possibly have unspecified other impact via a crafted year value to (1) the GregorianToSdn function in gregor.c or (2) the JulianToSdn function in julian.c, as demonstrated by a crafted third argument to the gregoriantojd or juliantojd function.
