An out-of-bounds write flaw was found in libtiff v4.0.6 when using tiffcp command to handle malicious tiff file. The vulnerability exists in function horizontalDifference8()
An attacker could control the head data of next heap which contains pre_size field and size filed to result in DoS or potential code execution.

Vulnerable code:


Source info

============
1082           wp += n + stride - 1;     /* point to last one */
1083           ip += n + stride - 1;       /* point to last one */
1084           n -= stride;
1085           while (n > 0) {
1086              REPEAT(stride, wp[0] = CLAMP(ip[0]);
1087                            wp[stride] -= wp[0];
1088                            wp[stride] &= mask;
1089                            wp--; ip--)
1090              n -= stride;
1091           }
1092           REPEAT(stride, wp[0] = CLAMP(ip[0]); wp--; ip--)

References:

http://seclists.org/oss-sec/2016/q2/57


Upstream bug:

http://bugzilla.maptools.org/show_bug.cgi?id=2544