Gentoo Linux Security Advisory GLSA 200507-20 – Shorewall fails to enforce security policies if configured with MACLIST_DISPOSITION set to ACCEPT or MACLIST_TTL set to a value greater or equal to 0. Versions less than 2.4.1 are affected.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/38840/glsa-200507-20.txt
Source: https://packetstormsecurity.com/files/38840/Gentoo-Linux-Security-Advisory-200507-20.html