nodemailer before 9.0.1 fails to apply disableFileAccess and disableUrlAccess flags to message-level raw option, allowing authenticated attackers to read arbitrary files or perform server-side request forgery by supplying path or href properties. Attackers can exploit this by crafting raw messages with file paths or URLs that bypass the intended sandbox, with fetched content delivered in the outgoing message to attacker-controlled recipients.

CVE-2026-82659 affects nodemailer versions before 9.0.1, where the disableFileAccess and disableUrlAccess security flags are not applied to the message-level raw option. This oversight allows authenticated attackers to supply path or href properties in crafted raw messages, enabling arbitrary file reads or server-side request forgery (SSRF). The vulnerability bypasses the intended sandbox restrictions, with fetched file or URL content being delivered in outgoing emails to attacker-controlled recipients. The attack requires authentication but can lead to significant data exfiltration or internal network reconnaissance via SSRF. The fix is available in nodemailer version 9.0.1 and above. Organizations using nodemailer in their applications should upgrade immediately to mitigate risk.