Exim 4.85 through 4.92 (fixed in 4.92.1) allows remote code execution as root in some unusual configurations that use the ${sort } expansion for items that can be controlled by an attacker (e.g., $local_part or $domain).
http://exim.org/static/doc/security/CVE-2019-13917.txt
http://www.openwall.com/lists/oss-security/2019/07/26/5
https://seclists.org/bugtraq/2019/Jul/51
Source: MITRE
Published: 2019-07-25
Updated: 2019-09-07
Type: CWE-19
Base Score: 10
Vector: AV:N/AC:L/Au:N/C:C/I:C/A:C
Impact Score: 10
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