CVE-2026-34757

Name	CVE-2026-34757
Description	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 png_get_PLTE, png_get_tRNS, or png_get_hIST back into the corresponding setter on the same png_struct/png_info 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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1133051

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
libpng1.6 (PTS)	bullseye	1.6.37-3	vulnerable
	bullseye (security)	1.6.37-3+deb11u3	vulnerable
	bookworm	1.6.39-2+deb12u1	vulnerable
	bookworm (security)	1.6.39-2+deb12u4	vulnerable
	trixie	1.6.48-1+deb13u3	vulnerable
	trixie (security)	1.6.48-1+deb13u4	vulnerable
	forky, sid	1.6.58-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libpng1.6	source	(unstable)	1.6.57-1			1133051

Notes

https://github.com/pnggroup/libpng/security/advisories/GHSA-6fr7-g8h7-v645
Fixed by: https://github.com/pnggroup/libpng/commit/398cbe3df03f4e11bb031e07f416dfdde3684e8a (v1.6.57)
Followup: https://github.com/pnggroup/libpng/commit/55d20aaa322c9274491cda82c5cd4f99b48c6bcc (v1.6.57)