Nodemailer (npm package "nodemailer") versions 9.1.0 and earlier do not honor the "disableFileAccess" and "disableUrlAccess" sandbox options when message content is resolved through the public plugin API "MailMessage.resolveContent()" using the documented legacy three-argument signature "resolveContent(data, key, callback)". Because "shared.resolveContent()" normalizes the missing "options" argument to an empty object, the message-level flags copied into "mail.data" by the MailMessage constructor are discarded, and "resolveContentValue()" skips both access-control checks, reaching "nmfetch(url)" or "fs.createReadStream(path)". As a result, plugin or application code that resolves untrusted message content (html, text, attachment "path" or "href") via this API can be induced to read arbitrary local files or issue outbound HTTP(S) requests (server-side request forgery), bypassing the sandbox the application enabled. The internal paths used by "transporter.sendMail()" ("resolveAll()", "_convertDataImages()", and the MIME streaming path) are not affected. Fixed in version 9.1.1.