CVE-2026-73639
Medium
Elevated severity or exploit probability.
Description
Imager::File::PNG versions from 1.003 before 1.004 for Perl write past the end of the row buffer reading a PNG with a tRNS transparency chunk in read_direct8. With a tRNS chunk, read_direct8() adds an alpha channel to the image it creates but still sizes the row buffer from the original channel count. libpng expands the transparency into that extra channel, so png_read_row() fills one channel more than the buffer holds, at one byte per sample, and writes width bytes past the end of the allocation. Palette images go to read_paletted() and 16-bit images to read_direct16(), which sizes its buffer from png_get_rowbytes() and allocates enough for the expanded row. The same reader ships bundled in the Imager distribution. Reading an attacker-supplied PNG through Imager->read() corrupts the heap, which can crash the process.
References
- https://github.com/tonycoz/imager/commit/d973bd7e8843f084e8071caa24b89545c88b1e4b.patch
- https://github.com/tonycoz/imager/pull/567
- https://github.com/tonycoz/imager/security/advisories/GHSA-jhx5-34j8-9g88
- https://metacpan.org/release/TONYC/Imager-1.035/changes
- https://metacpan.org/release/TONYC/Imager-File-PNG-1.004/changes
- http://www.openwall.com/lists/oss-security/2026/09/17/6