Imager versions before 1.037 for Perl overflow a heap buffer fetching float samples from a paletted image in i_gsampf_fp. For a paletted image, getsamples() with type "float" allocates a buffer of one sample per pixel and fetches every requested channel of each pixel into it. Requesting more than one channel writes past its end. An attacker-supplied image controls the overflowing bytes through its palette.
https://metacpan.org/release/TONYC/Imager-1.037/changes
https://github.com/tonycoz/imager/security/advisories/GHSA-4rx6-cgv3-fmxp
https://github.com/tonycoz/imager/commit/aae49c6be065aa467e834105c816359394a634db.patch