The is_utf8_well_formed function in GNU less before 475 allows remote attackers to have unspecified impact via malformed UTF-8 characters, which triggers an out-of-bounds read.

Format string bug in the open_altfile function in filename.c for GNU less 382, 381, and 358 might allow local users to cause a denial of service or possibly execute arbitrary code via format strings in the LESSOPEN environment variable. NOTE: since less is not setuid or setgid, then this is not a vulnerability unless there are plausible scenarios under which privilege boundaries could be crossed