CVE-2026-34757: LIBPNG has a yse-after-free in png_set_PLTE, png_set_tRNS and png_set_hIST leading to corrupted chunk data and potential heap information disclosure

LIBPNG has a yse-after-free in pngsetPLTE, pngsettRNS and pngsethIST leading to corrupted chunk data and potential heap information disclosure

— Microsoft

LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. From 1.0.9 to before 1.6.57, passing a pointer obtained from pnggetPLTE, pnggettRNS, or pnggethIST back into the corresponding setter on the same pngstruct/pnginfo pair causes the setter to read from freed memory and copy its contents into the replacement buffer. The setter frees the internal buffer before copying from the caller-supplied pointer, which now dangles. The freed region may contain stale data (producing silently corrupted chunk metadata) or data from subsequent heap allocations (leaking unrelated heap contents into the chunk struct). This vulnerability is fixed in 1.6.57.

— MITRE