NGINX must only allow using DOD approved certificate authorities for PKI.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-278403	SRG-APP-000427	NGNX-APP-001900	SV-278403r1171961_rule	2026-01-07	1

Description
Untrusted Certificate Authorities (CA) can issue certificates, but they may be issued by organizations or individuals that seek to compromise DOD systems or by organizations with insufficient security controls. If the CA used for verifying the certificate is not a DOD-approved CA, trust of this CA has not been established. The DOD will only accept PKI certificates obtained from a DOD-approved internal or external certificate authority. Reliance on CAs for the establishment of secure sessions includes, for example, using TLS certificates. This requirement focuses on communications protection for the application session rather than for the network packet. This requirement applies to applications that use communications sessions. This includes, but is not limited to, web-based applications and service-oriented architectures (SOAs). Satisfies: SRG-APP-000427, SRG-APP-000177, SRG-APP-000910

Description

Untrusted Certificate Authorities (CA) can issue certificates, but they may be issued by organizations or individuals that seek to compromise DOD systems or by organizations with insufficient security controls. If the CA used for verifying the certificate is not a DOD-approved CA, trust of this CA has not been established. The DOD will only accept PKI certificates obtained from a DOD-approved internal or external certificate authority. Reliance on CAs for the establishment of secure sessions includes, for example, using TLS certificates. This requirement focuses on communications protection for the application session rather than for the network packet. This requirement applies to applications that use communications sessions. This includes, but is not limited to, web-based applications and service-oriented architectures (SOAs). Satisfies: SRG-APP-000427, SRG-APP-000177, SRG-APP-000910

ℹ️ Check
Determine the path to NGINX config file(s): # nginx -qT \| grep "# configuration" # configuration file /etc/nginx/nginx.conf: Note: The default NGINX configuration is "/etc/nginx/nginx.conf", though various files may also be included. Find any "ssl_certificate" ssl_client_certificate" directives and verify they are DOD approved. If the certificates are not DOD approved, this is a finding.

✔️ Fix
Replace any non-DOD issued certificates with DOD-issued certificates. After replacing the certificates, reload NGINX: # nginx -s reload