CVE-2026-34757 is a use-after-free vulnerability in libpng occurring when an application reuses pointers from functions like png_get_PLTE, png_get_tRNS, or png_get_hIST and passes them to their corresponding setter functions within the same PNG image structure. This causes the setter to access memory that has already been freed, resulting in potential memory corruption or information disclosure. The vulnerability is local and requires user interaction to open a crafted PNG image. Red Hat has rated the impact as moderate due to limited attacker control over exfiltrated content or memory corruption. The advisory covers Red Hat Hardened Images RPMs including libpng-1.6.57-0.1.hum1 for aarch64 and x86_64 architectures. No patch or mitigation meeting Red Hat’s criteria is currently available.

A local attacker who can trick a user into opening a maliciously crafted PNG image may exploit this use-after-free vulnerability to cause memory corruption or disclose sensitive information from the application's memory. The attacker does not have full control over the corrupted memory or the data exfiltrated. The impact is rated as moderate by Red Hat Product Security.

Currently, no mitigation or patch meeting Red Hat's criteria for ease of use, deployment, applicability, or stability is available. Users should apply the update once it becomes available from Red Hat. Until then, avoid opening untrusted PNG images with vulnerable applications.