CVE-2026-110871 — Nodemailer 3.0.0 before 10.0.10 Quadratic DKIM Header Unfolding Denial of Service
Nodemailer from 3.0.0 before 10.0.10 contains a denial of service vulnerability in MessageParser.parseHeaders that allows users to exhaust CPU through quadratic header unfolding. Attackers can supply large recipient lists or long headers that fold into tens of thousands of continuation lines, blocking the Node.js event loop during DKIM signing.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Nodemailer Nodemailer).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (denial of service), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Nodemailer | Nodemailer | ≥ 3.0.0 and < 10.0.10 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.1 | CVSS 4.0 | High | — | — | disclosure@vulncheck.com via NIST National Vulnerability Database |
| 7.1 | CVSS 4.0 | High | — | — | VulnCheck via CVE Program (cve.org) e CISA ADP |
| 6.5 | CVSS 3.1 | Medium | 2.8 | 3.6 | disclosure@vulncheck.com via NIST National Vulnerability Database |
| 6.5 | CVSS 3.1 | Medium | — | — | VulnCheck via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (score shown at the top: disclosure@vulncheck.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Track CPU/memory spikes and availability drops correlated with request patterns.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · nodemailer/nodemailer
- Record published
- CVSS changed · 6.5
- Source status changed · → Received
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× References added · Oct 14, 2026 – Oct 14, 2026
- 1× Official description updated · Oct 14, 2026 – Oct 14, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-110872 Nodemailer 3.0.0 before 10.0.10 Denial of Service via SMTP Reply Parsing 18h
- High CVE-2026-110869 Nodemailer 3.0.0 before 10.0.13 ReDoS via SMTP AUTH Mechanism Detection Regexes 18h
- Medium CVE-2026-110870 Nodemailer before 10.0.13 Improper Input Validation via Angle-Bracket Address Comments 18h
- Critical CVE-2026-82854 Nodemailer before 8.0.3 SMTP Command Injection via envelope.size Aug 31, 2026
- High CVE-2025-14874 Nodemailer: nodemailer: denial of service via crafted email address header Dec 18, 2025
- High CVE-2025-13033 Nodemailer: nodemailer: email to an unintended domain can occur due to interpretation conflict Nov 14, 2025
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No FIRST EPSS score.
- No fixed version, patch or mitigation documented.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-110871 is "Nodemailer 3.0.0 before 10.0.10 Quadratic DKIM Header Unfolding Denial of Service", rated Medium. It affects Nodemailer (Nodemailer); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.5 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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