Nodemailer before 9.1.0 Email Domain Validation Bypass via RFC 5322 Comment

{
  "id": "569cb2600907cb22de0edd745816f75471021b51afb4c3038d52e74c7e2c9a71",
  "url": "https://osv.dev/vulnerability/CVE-2026-92597",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Nodemailer before 9.1.0 Email Domain Validation Bypass via RFC 5322 Comment",
    "summary": "Nodemailer versions >= 6.9.16 and < 9.1.0 mis-parse RFC 5322 comments in email addresses: in lib/addressparser, a comment closed immediately before a non-break character causes the tokenizer to concatenate the atoms surrounding the comment instead of treating the comment as folding whitespace that terminates the domain. A recipient address such as user@good-corp.com(x)evil.com is therefore read by Nodemailer as the single domain good-corp.comevil.com (registrable domain comevil.com, which an attacker can register) and used for both the SMTP envelope (RCPT TO) and the emitted To:/From: headers, while a conformant RFC 5322 parser terminates the domain at the comment and reads good-corp.com. An application that validates the recipient domain with a strict RFC 5322 parser (without inspecting parse defects) or a naive prefix/substring allow-list and then hands the raw address to Nodemailer can be induced to deliver mail to a domain the attacker controls. Fixed in 9.1.0.",
    "evidence": "osv:CVE-2026-92597",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-92597",
      "aliases": [
        "CVE-2026-92597",
        "GHSA-cc9r-2j5m-2m83"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/nodemailer/nodemailer",
              "type": "GIT",
              "events": [
                {
                  "introduced": "e70b9c18bd4ba14d500197fa1614ed37f5536446"
                },
                {
                  "fixed": "efd6e29c10c6e0c25c57bd2f2a71302838235a4f"
                },
                {
                  "fixed": "902b63e"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "6.9.16"
                      },
                      {
                        "fixed": "9.1.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "902b63e"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v9.0.6",
            "v9.0.5",
            "v9.0.4",
            "v9.0.3",
            "v9.0.2",
            "v9.0.1",
            "v9.0.0",
            "v8.0.11",
            "v8.0.10",
            "v8.0.9",
            "v8.0.8",
            "v8.0.7",
            "v8.0.6",
            "v8.0.5",
            "v8.0.4",
            "v8.0.3",
            "v8.0.2",
            "v8.0.1",
            "v8.0.0",
            "v7.0.13",
            "v7.0.12",
            "v7.0.11",
            "v7.0.10",
            "v7.0.9",
            "v7.0.7",
            "v7.0.6",
            "v7.0.5",
            "v6.9.16"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-92597.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.110189514Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/92xxx/CVE-2026-92597.json",
        "https://github.com/nodemailer/nodemailer/security/advisories/GHSA-cc9r-2j5m-2m83",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-92597",
        "https://www.vulncheck.com/advisories/nodemailer-before-9.1.0-email-domain-validation-bypass-via-rfc-5322-comment",
        "https://github.com/nodemailer/nodemailer/commit/902b63e"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-436"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/92xxx/CVE-2026-92597.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-92597",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 517520,
  "published_at": "2026-09-16T21:47:01.599+00:00"
}