CVE-2015-8472

In png_set_tRNS of pngset.c, there is a possible memory corruption due to a use-after-free. This could lead to remote code execution with no additional execution privileges needed.

In libpng versions 1.6.36 through 1.6.55, the ARM/AArch64 Neon-optimized palette expansion path has an out-of-bounds read and write. When expanding the final partial chunk of an 8-bit paletted row, pointers are dereferenced before the row buffer start and expanded data is written out of bounds, reachable via decoding attacker-controlled PNG input when Neon is enabled. Version 1.6.56 fixes the issue.

In libpng versions 1.2.1 through 1.6.55, `png_set_tRNS` and `png_set_PLTE` each alias a heap-allocated buffer between `png_struct` and `png_info`, sharing a single allocation across two structs with independent lifetimes. Calling `png_free_data` (with `PNG_FREE_TRNS` or `PNG_FREE_PLTE`) frees the buffer through `info_ptr` while the corresponding `png_ptr` pointer remains dangling, and subsequent row-transform functions dereference and in some code paths write to the freed memory. A second call to `png_set_tRNS` or `png_set_PLTE` has the same effect because both functions internally call `png_free_data` before reallocating the `info_ptr` buffer. Version 1.6.56 fixes the issue.

The png_set_text_2 function in libpng before versions 1.0.67, 1.2.57, 1.4.20, 1.5.28, and 1.6.27 allows context-dependent attackers to cause a NULL pointer dereference. This issue occurs when loading a text chunk into a png structure, removing the text, and then adding another text chunk.

Unspecified vulnerability in libpng before version 1.6.20, used in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before July 1, 2016, allows attackers to gain privileges via a crafted application.

An integer underflow in the png_check_keyword function in pngwutil.c in libpng allows remote attackers to trigger an out-of-bounds read by using a space character as a keyword in a PNG image.

Buffer overflow in the png_read_IDAT_data function in pngrutil.c in libpng before 1.5.21 and 1.6.x before 1.6.16 allows context-dependent attackers to execute arbitrary code via IDAT data with a large width.

Heap-based buffer overflow in the png_combine_row function in libpng before 1.5.21 and 1.6.x before 1.6.16 may allow context-dependent attackers to execute arbitrary code via a 'very wide interlaced' PNG image on 64-bit systems.

Multiple buffer overflows in the png_set_PLTE and png_get_PLTE functions in libpng before version 1.0.64 and in versions 1.1.x, 1.2.x, 1.3.x, 1.4.x, 1.5.x, and 1.6.x before their respective versions may allow remote attackers to cause application crashes or potentially other unspecified impacts via a small bit-depth value in an IHDR (image header) chunk in a PNG image.

LIBPNG version 1.8.0 has a bug in the push-mode APNG parser: three inter-frame chunk discard paths do not consume the chunk body and CRC, allowing attacker-controlled bytes inside an ignored ancillary chunk to be reinterpreted as a fresh chunk header on the next call to png_process_data.