WEBrick::HTTPAuth::DigestAuth in Ruby through 2.4.7, 2.5.x through 2.5.6, and 2.6.x through 2.6.4 has a regular expression Denial of Service cause by looping/backtracking. A victim must expose a WEBrick server that uses DigestAuth to the Internet or a untrusted network.
http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00041.html
https://hackerone.com/reports/661722
https://lists.debian.org/debian-lts-announce/2019/11/msg00025.html
https://lists.debian.org/debian-lts-announce/2019/12/msg00009.html
https://lists.debian.org/debian-lts-announce/2020/08/msg00027.html
https://seclists.org/bugtraq/2019/Dec/31
https://seclists.org/bugtraq/2019/Dec/32
https://security.gentoo.org/glsa/202003-06
Source: MITRE
Published: 2019-11-26
Updated: 2020-08-16
Type: CWE-287
Base Score: 7.8
Vector: AV:N/AC:L/Au:N/C:N/I:N/A:C
Impact Score: 6.9
Exploitability Score: 10
Severity: HIGH
Base Score: 7.5
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Impact Score: 3.6
Exploitability Score: 3.9
Severity: HIGH