RubyGems versions between 2.0.0 and 2.6.13 are vulnerable to a possible remote code execution vulnerability. YAML deserialization of gem specifications can bypass class white lists. Specially crafted serialized objects can possibly be used to escalate to remote code execution.
http://blog.rubygems.org/2017/10/09/2.6.14-released.html
http://blog.rubygems.org/2017/10/09/unsafe-object-deserialization-vulnerability.html
http://www.securityfocus.com/bid/101275
https://access.redhat.com/errata/RHSA-2017:3485
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://github.com/rubygems/rubygems/commit/510b1638ac9bba3ceb7a5d73135dafff9e5bab49
https://hackerone.com/reports/274990
https://lists.debian.org/debian-lts-announce/2018/07/msg00012.html
https://usn.ubuntu.com/3553-1/
Source: MITRE
Published: 2017-10-11
Updated: 2019-10-09
Type: CWE-502
Base Score: 7.5
Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P
Impact Score: 6.4
Exploitability Score: 10
Severity: HIGH
Base Score: 9.8
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Impact Score: 5.9
Exploitability Score: 3.9
Severity: CRITICAL