CVE-2026-19082: Imager versions from 0.45_02 before 1.034 for Perl may expose adjacent heap bytes via strlen() over-read from zero-count ASCII EXIF entries in copy_string_tags

Imager versions from 0.4502 before 1.034 for Perl may expose adjacent heap bytes via strlen() over-read from zero-count ASCII EXIF entries in copystringtags.

copystringtags() computes an ASCII EXIF tag's length as entry->size - 1 to strip the trailing NUL. A zero-count ASCII entry sets entry->size to 0, and the derived length reaches itagsadd() as -1, which is interpreted as a request to call strlen(), scanning past the entry to the next NUL and copying those bytes into the tag. JPEG reaches this path via imdecodeexif(), as does the separate Imager::File::WEBP distribution, which is fixed by upgrading Imager.

Any caller of Imager->read() on an attacker-supplied image with such an entry may receive an exif tag holding adjacent heap bytes instead of an empty string.