Inefficient regular expression complexity in nodemailer - CVE-2026-100700
Published: September 30, 2026
Vulnerability identifier: #VU153016
CSH Severity: Medium
CVSS v4: 8.7 [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]
CVE-ID: CVE-2026-100700
CWE-ID: CWE-1333
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to inefficient regular expression complexity in the addressparser free-text fallback when parsing crafted address header values. A remote attacker can submit a crafted whitespace-free input string that causes quadratic backtracking to cause a denial of service.
The resulting event-loop blockage can stall the entire Node.js process.
Affected software
nodemailer
How to mitigate CVE-2026-100700
Install security update from vendor's website.
nodemailer - update to 10.0.6