libpng: libpng: Arbitrary code execution due to use-after-free vulnerability
Details
CVSS v3
7.5
NVD published
2026-03-26 17:16:38
EPSS
<0.1% probability · 12.0th percentile — 2026-05-03
Affected versions
cpe:2.3:a:libpng:libpng:*:*:*:*:*:*:*:*
Summary
LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.2.1 through 1.6.55, `png_set_tRNS` and `png_set_PLTE` each alias a heap-allocated buffer between `png_struct` and `png_info`, sharing a single allocation across two structs with independent lifetimes. The `trans_alpha` aliasing has been present since at least libpng 1.0, and the `palette` aliasing since at least 1.2.1. Both affect all prior release lines `png_set_tRNS` sets `png_ptr->trans_alpha = info_ptr->trans_alpha` (256-byte buffer) and `png_set_PLTE` sets `info_ptr->palette = png_ptr->palette` (768-byte buffer). In both cases, calling `png_free_data` (with `PNG_FREE_TRNS` or `PNG_FREE_PLTE`) frees the buffer through `info_ptr` while the corresponding `png_ptr` pointer remains dangling. Subsequent row-transform functions dereference and, in some code paths, write to the freed memory. A second call to `png_set_tRNS` or `png_set_PLTE` has the same effect, because both functions call `png_free_data` internally before reallocating the `info_ptr` buffer. Version 1.6.56 fixes the issue.
TopVuln sends digest emails with high-risk CVE picks across multiple authoritative sources—curated with EPSS and AI. Choose daily per-stream emails and optional weekly or monthly roundups.