The png_set_text_2 function in libpng 0.71 before 1.0.67, 1.2.x before 1.2.57, 1.4.x before 1.4.20, 1.5.x before 1.5.28, and 1.6.x before 1.6.27 allows context-dependent attackers to cause a NULL pointer dereference vectors involving loading a text chunk into a png structure, removing the text, and then adding another text chunk to the structure.

Integer underflow in the png_check_keyword function in pngwutil.c in libpng 0.90 through 0.99, 1.0.x before 1.0.66, 1.1.x and 1.2.x before 1.2.56, 1.3.x and 1.4.x before 1.4.19, and 1.5.x before 1.5.26 allows remote attackers to have unspecified impact via a space character as a keyword in a PNG image, which triggers an out-of-bounds read.

The png_convert_to_rfc1123 function in png.c in libpng 1.0.x before 1.0.64, 1.2.x before 1.2.54, and 1.4.x before 1.4.17 allows remote attackers to obtain sensitive process memory information via crafted tIME chunk data in an image file, which triggers an out-of-bounds read.

The png_push_read_zTXt function in pngpread.c in libpng 1.0.x before 1.0.58, 1.2.x before 1.2.48, 1.4.x before 1.4.10, and 1.5.x before 1.5.10 allows remote attackers to cause a denial of service (out-of-bounds read) via a large avail_in field value in a PNG image.

The png_set_text_2 function in pngset.c in libpng 1.0.x before 1.0.59, 1.2.x before 1.2.49, 1.4.x before 1.4.11, and 1.5.x before 1.5.10 allows remote attackers to cause a denial of service (crash) or execute arbitrary code via a crafted text chunk in a PNG image file, which triggers a memory allocation failure that is not properly handled, leading to a heap-based buffer overflow.

Memory leak in pngwutil.c in libpng 1.2.13beta1, and other versions before 1.2.15beta3, allows context-dependent attackers to cause a denial of service (memory leak or segmentation fault) via a JPEG image containing an iCCP chunk with a negative embedded profile length.

libpng 1.0.6 through 1.0.32, 1.2.0 through 1.2.26, and 1.4.0beta01 through 1.4.0beta19 allows context-dependent attackers to cause a denial of service (crash) and possibly execute arbitrary code via a PNG file with zero length "unknown" chunks, which trigger an access of uninitialized memory.

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.