Exim 4 before 4.94.2 allows Use After Free in smtp_reset in certain situations that may be common for builds with OpenSSL.
https://www.exim.org/static/doc/security/CVE-2020-qualys/CVE-2020-28018-OCORK.txt
http://www.openwall.com/lists/oss-security/2021/05/11/5
http://www.openwall.com/lists/oss-security/2021/05/11/6
http://www.openwall.com/lists/oss-security/2021/05/11/17
http://www.openwall.com/lists/oss-security/2021/05/11/15
http://www.openwall.com/lists/oss-security/2021/05/11/14
Source: MITRE
Published: 2021-05-06
Updated: 2021-05-26
Type: CWE-416
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:3.1/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