{"id":"GHSA-fv2f-rw9f-v9cm","summary":"smtp-server's command parser memory exhaustion denial-of-service","details":"smtp-server prior to v3.18.3 are vulnerable to unauthenticated memory exhaustion denial-of-service. smtp-server's command parser allows any remote client to consume server memory by sending data without newline characters. The server's `_remainder` buffer in `SMTPStream._write` grows without limit, leading to heap exhaustion, prolonged GC pauses that freeze the event loop, and in some cases, process crash.\n\nThe `_write` method in `lib/smtp-stream.js` appends incoming TCP chunks to `this._remainder` in command mode. The buffer is only emptied when a newline is found. If a client never sends a newline, the `_remainder` value will grow indefinitely, causing excess memory consumption.","aliases":["CVE-2026-38728"],"modified":"2026-06-29T23:26:32.795552Z","published":"2026-05-15T15:30:45Z","database_specific":{"nvd_published_at":"2026-05-15T15:16:51Z","cwe_ids":["CWE-400"],"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-06-29T22:57:15Z"},"references":[{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-38728"},{"type":"WEB","url":"https://github.com/nodemailer/smtp-server/commit/592c5666fa0c76d1d04c1a32abad0ef806fbfe97"},{"type":"WEB","url":"https://bytecreator.dev/blog/CVE-2026-38728"},{"type":"PACKAGE","url":"https://github.com/nodemailer/smtp-server"},{"type":"WEB","url":"https://github.com/nodemailer/smtp-server/releases/tag/v3.18.3"}],"affected":[{"package":{"name":"smtp-server","ecosystem":"npm","purl":"pkg:npm/smtp-server"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.18.3"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-fv2f-rw9f-v9cm/GHSA-fv2f-rw9f-v9cm.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}