The decode method in the OpenSSL::ASN1 module in Ruby before 2.2.8, 2.3.x before 2.3.5, and 2.4.x through 2.4.1 allows attackers to cause a denial of service (interpreter crash) via a crafted string.
https://access.redhat.com/errata/RHSA-2018:0378
https://access.redhat.com/errata/RHSA-2018:0583
https://access.redhat.com/errata/RHSA-2018:0585
https://lists.debian.org/debian-lts-announce/2018/07/msg00012.html
https://security.gentoo.org/glsa/201710-18
https://www.debian.org/security/2017/dsa-4031