CVE-2022-28321: 
NixOS vulnerability analysis and mitigation

The Linux-PAM package before version 1.5.2-6.1 for openSUSE Tumbleweed contains a vulnerability that allows authentication bypass for SSH logins. This security issue was discovered in early 2022 and primarily affects openSUSE Tumbleweed and openSUSE Factory distributions (NVD, SUSE Security).

The vulnerability exists in the pam_access.so module, which fails to properly restrict login attempts when a user tries to connect from an IP address that is not resolvable via DNS. The issue has been assigned a CVSS v3.1 base score of 9.8 (Critical) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, indicating network accessibility, low attack complexity, and no required privileges or user interaction (NVD).

When exploited, this vulnerability allows users with denied access to a machine to bypass authentication restrictions and gain unauthorized access to the system. The high severity rating indicates potential complete compromise of system confidentiality, integrity, and availability (NVD).

The issue has been fixed in Linux-PAM version 1.5.2-6.1 and later. The fix was implemented through a patch that corrects the IP address resolution handling in the pam_access.so module. Organizations running affected versions should upgrade to the patched version (SUSE Security).