Constructed ASN.1 types with a recursive definition (such as can be found in PKCS7) could eventually exceed the stack given malicious input with excessive recursion. This could result in a Denial Of Service attack. There are no such structures used within SSL/TLS that come from untrusted sources so this is considered safe. Fixed in OpenSSL 1.1.0h (Affected 1.1.0-1.1.0g). Fixed in OpenSSL 1.0.2o (Affected 1.0.2b-1.0.2n).
https://www.tenable.com/security/tns-2018-07
https://www.tenable.com/security/tns-2018-06
https://www.tenable.com/security/tns-2018-04
https://www.oracle.com/technetwork/security-advisory/cpujul2019-5072835.html
https://www.oracle.com/technetwork/security-advisory/cpujan2019-5072801.html
https://www.oracle.com/technetwork/security-advisory/cpuapr2019-5072813.html
https://www.oracle.com//security-alerts/cpujul2021.html
https://www.openssl.org/news/secadv/20180327.txt
https://www.debian.org/security/2018/dsa-4158
https://www.debian.org/security/2018/dsa-4157
https://usn.ubuntu.com/3611-2/
https://usn.ubuntu.com/3611-1/
https://securityadvisories.paloaltonetworks.com/Home/Detail/133
https://security.netapp.com/advisory/ntap-20180726-0002/
https://security.netapp.com/advisory/ntap-20180330-0002/
https://security.gentoo.org/glsa/202007-53
https://security.gentoo.org/glsa/201811-21
https://nodejs.org/en/blog/vulnerability/march-2018-security-releases/
https://lists.debian.org/debian-lts-announce/2018/03/msg00033.html
https://access.redhat.com/errata/RHSA-2019:1712
https://access.redhat.com/errata/RHSA-2019:1711
https://access.redhat.com/errata/RHSA-2019:0367
https://access.redhat.com/errata/RHSA-2019:0366
https://access.redhat.com/errata/RHSA-2018:3505
https://access.redhat.com/errata/RHSA-2018:3221
https://access.redhat.com/errata/RHSA-2018:3090
http://www.securitytracker.com/id/1040576
http://www.securityfocus.com/bid/105609
http://www.securityfocus.com/bid/103518
http://www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.html
http://www.oracle.com/technetwork/security-advisory/cpujul2018-4258247.html
http://www.oracle.com/technetwork/security-advisory/cpuapr2018-3678067.html