Certain chunk handlers in libpng before 1.0.29 and 1.2.x before 1.2.21 allow remote attackers to cause a denial of service (crash) via crafted (1) pCAL (png_handle_pCAL), (2) sCAL (png_handle_sCAL), (3) tEXt (png_push_read_tEXt), (4) iTXt (png_handle_iTXt), and (5) ztXT (png_handle_ztXt) chunking in PNG images, which trigger out-of-bounds read operations.
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.