There is a heap-based buffer over-read in the Exiv2::Internal::PngChunk::keyTXTChunk function of pngchunk_int.cpp in Exiv2 0.26. A crafted PNG file will lead to a remote denial of service attack.
https://usn.ubuntu.com/3852-1/
https://lists.debian.org/debian-lts-announce/2023/01/msg00004.html