The GD Graphics Library (aka LibGD) 2.2.5 has a double free in the gdImage*Ptr() functions in gd_gif_out.c, gd_jpeg.c, and gd_wbmp.c. NOTE: PHP is unaffected.
"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2019-6978.json"