Security · libpng
libpng's simplified 8-bit write over-reads its row buffer
LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files.
- Advisory
- CVE-2025-64506
- Library
- libpng, libpng1.6 on Debian
- Published
- Severity
- 6.1 out of 10, as published
- Affected
- libpng 1.6.0 to before 1.6.51
- Fixed in
- 1.6.51
- Reaches you
- on a save path
What triggers it
Writing an 8-bit image through libpng's simplified write API with convert_to_8bit set.
What sillybos does
Not reached by opening a file
Opening or reading a file never reaches this flaw, so a check before decoding has nothing to refuse. Listed so that nobody expects it to.
On the write path only; reading a PNG never runs png_write_image_8bit.
Proposed from the advisory's text on 2026-11-01, as part of folding the backfill into the record; confirmed by a person on 2026-11-03.
How to protect yourself
In general. Upgrade to libpng 1.6.51.
Specifically. Not a pre-decode matter: the flaw is on a save path.
The general advice applies to every row here.
Sources
- https://osv.dev/vulnerability/DEBIAN-CVE-2025-64506
- The record entry, triaged 2026-11-03, last checked 2026-11-03