Nodemailer before 10.0.9 Malformed Envelope Recipient via RFC 5322 Comment
CVSS score
6.9
EPSS probability
%0.2
Risk score
0.0
Published
16 d ago
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Vulnerability description
DayBreach CVE AI Research
CVE-2026-100699 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.
Nodemailer is a Node.js email-sending library. In versions >= 9.1.0 and < 10.0.9, the address parser (src/addressparser) mishandles addresses whose local-part is a quoted string and that are followed by RFC 5322 comments, allowing trailing comment-separated domain atoms to be retained in the normalized address. For example, the input "user"@example.com(x)evil.com is parsed to the address value 'user@example.com evil.com', which contains additional attacker-controlled domain text separated by a literal space. This parsed value is used without further strict recipient validation when the message envelope is built (envelope.to in src/mime-node), so a malformed/ambiguous recipient address can be accepted and placed in the SMTP envelope. Whether this results in delivery to an unintended recipient on real SMTP servers has not been confirmed. The issue is a variant of the RFC 5322 comment parsing problem addressed in GHSA-cc9r-2j5m-2m83, affecting the separate quoted-local-part code path. Version 10.0.9 contains a fix.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-100699 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
| ID | VENDOR | PRODUCT | ACTION |
|---|---|---|---|
| 1 | nodemailer | nodemailer | View |
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 6.9 | CVSS V4_0 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N | CVE CNA |
| 6.9 | CVSS V40 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD |
| 5.3 | CVSS V3_1 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N | CVE CNA |
| 5.3 | CVSS V31 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N | NVD |
Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-100699 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-100699 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
CVSS Vector Radar Chart
6.9 / 10Vulnerability Scoring Details
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:NYama durumu bilinmiyor
Weakness Type (CWE & CAPEC)
Similar Vulnerabilities
Nodemailer before 8.0.3 SMTP Command Injection via envelope.size
Nodemailer before 9.1.0 Denial of Service via addressparser
Nodemailer before 8.0.5 SMTP Command Injection via CRLF
Nodemailer 9.1.0 through 10.0.4 Denial of Service via Quadratic Address Parsing
Vulnerability in Nodemailer
Nodemailer before 9.1.0 IDN/Punycode Domain Allow-list Bypass
Get this vulnerability through the API
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curl -H "x-api-key: $DAYBREACH_API_KEY" \ "https://api.enginteksut.com.tr/api/v1/intel/cves/CVE-2026-100699"