A flaw was found in dash. When built without libc fnmatch, the internal pmatch() matcher implements * by unbounded recursion over candidate positions. A local user who can plant filenames, or otherwise feed that matcher, can make a short multi-star pattern such as ....*.tar.gz consume excessive CPU.
Rebuild dash with --enable-fnmatch so pathname matching uses libc fnmatch. Until then, do not run dash globs, case, or ${var#pat} / ${var%pat} against attacker-controlled names with multi-star patterns. There is no upstream backtracking bound in the internal matcher.