Medium severity · published Oct 14, 2026
CVE-2026-110871
Nodemailer 3.0.0 before 10.0.10 Quadratic DKIM Header Unfolding Denial of Service
6.5
CVSS
0.4%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 32% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NO
nodemailer · nodemailer
3.0.0 before 10.0.10 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-110871
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-110871
github.com
https://github.com/nodemailer/nodemailer/security/advisories/GHSA-39m8-27wv-hr27
www.vulncheck.com
https://www.vulncheck.com/advisories/nodemailer-3.0.0-before-10.0.10-quadratic-dkim-header-unfolding-denial-of-service
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