A vulnerability was found in htmldoc version 1.9.15 where the stack out-of-bounds read takes place in gif_get_code() and occurs when opening a malicious GIF file, which can result in a crash (segmentation fault).
https://lists.debian.org/debian-lts-announce/2022/02/msg00022.html
https://github.com/michaelrsweet/htmldoc/issues/463
https://github.com/michaelrsweet/htmldoc/commit/312f0f9c12f26fbe015cd0e6cefa40e4b99017d9