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Vulnerability · Published Apr 9, 2026 · Assigned by GitHub_M

CVE-2026-34757LIBPNG 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

Medium 5.1

In plain English

A medium-severity use-after-free in libpng from pnggroup. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 10% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.1Medium
Exploit odds (30 days)0.2%top 90.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.20libpng1.6.57-r0ALPINE-CVE-2026-34757
Alpine:v3.21libpng1.6.57-r0ALPINE-CVE-2026-34757
Alpine:v3.22libpng1.6.57-r0ALPINE-CVE-2026-34757
Alpine:v3.23libpng1.6.57-r0ALPINE-CVE-2026-34757
Alpine:v3.24libpng1.6.57-r0ALPINE-CVE-2026-34757
Debian:12libpng1.61.6.39-2+deb12u5DEBIAN-CVE-2026-34757
Debian:13libpng1.61.6.48-1+deb13u5DEBIAN-CVE-2026-34757
Debian:14libpng1.61.6.57-1DEBIAN-CVE-2026-34757
Ubuntu:22.04:LTSlibpng1.61.6.37-3ubuntu0.5UBUNTU-CVE-2026-34757
Ubuntu:24.04:LTSlibpng1.61.6.43-5ubuntu0.6UBUNTU-CVE-2026-34757
Ubuntu:25.10libpng1.61.6.50-1ubuntu0.5UBUNTU-CVE-2026-34757

Affected products (as reported)

VendorProductVersions
pnggroup libpng >= 1.0.9, < 1.6.57

Weakness: CWE-416 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

References