CISA KEV catalog of actively exploited CVEs as JSON, filterable by vendor, with CWE and due dates.
CISA Known Exploited Vulnerabilities API is a free Security API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.

Unified API suite · now live
Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
Yes. The CISA Known Exploited Vulnerabilities API is listed in the Security category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
Yes. The CISA Known Exploited Vulnerabilities API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the CISA Known Exploited Vulnerabilities API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The CISA Known Exploited Vulnerabilities API is served over HTTPS, so it's safe to use in production.