#VU125602 Use-after-free in libpng - CVE-2026-34757

Description

The vulnerability allows a remote attacker to disclose heap information and corrupt chunk data.

The vulnerability exists due to use-after-free in png_set_PLTE, png_set_tRNS, and png_set_hIST when passing a pointer returned by the corresponding getter back into the setter on the same png_struct/png_info pair. A remote attacker can pass an aliased pointer to cause the library to read freed memory and copy stale or unrelated heap contents into replacement storage to disclose heap information and corrupt chunk data.

The issue cannot be triggered by a crafted PNG file alone; exploitation requires the application to call the getter and setter in sequence on the same struct pair, and any image containing the relevant chunk is sufficient to set up the internal pointer.

Remediation

External links

• https://github.com/pnggroup/libpng/security/advisories/GHSA-6fr7-g8h7-v645
• https://github.com/advisories/GHSA-6fr7-g8h7-v645