Unverified indexs into the array lead to out of bound access in the gif_out_code function in fromgif.c in libsixel 1.8.6.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-19668
Reference (s):
- https://github.com/saitoha/libsixel/issues/136