What:
js.org and (many of) its subdomains fail to restrict attackers from sending fraudulent e-mails.

Why:
The main js.org domain has a DMARC policy of "none"
Subdomains, such as npm.js.org, fail to specify both SPF and DMARC

Impact
Fraudulent e-mails can have an impact on

• Integrity; The attackers can exploit the trust js.org (and subdomains) holds with all of the contributors, this trust could deteriorate.
• Availability; Sites that have been abused for spam or phishing will be blocked in spam filters, this could trigger the domains to be blocked by firewalls as "malicious".

More information:
A lot of resources offer strong advice on e-mail security policies,
One such service is https://internet.nl

• Tests: https://internet.nl/mail/js.org/1609358/, https://internet.nl/mail/npm.js.org/1609360/
• Knowledge base: https://internet.nl/faqs/mailauth/