TI-2026-74559 Aliases CVE-2026-110869

ReDoS in Nodemailer SMTP AUTH mechanism detection regexes

HIGH 77CWE-1333Published 2026-10-14 · Updated 2026-10-15

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Partial Red Hat: 1 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-1333.

Summary

Nodemailer from 3.0.0 before 10.0.13 is affected by a regular expression denial of service (CWE-1333). The four AUTH mechanism detection regexes in SMTPConnection._actionEHLO contain overlapping whitespace sub-patterns that backtrack quadratically. A malicious or man-in-the-middle SMTP server that replies to EHLO with a long whitespace run and a non-matching token can block the Node.js event loop for tens of seconds to hours before authentication.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

Nodemailer 3.0.0 before 10.0.13 has a regular expression denial of service in SMTPConnection._actionEHLO, whose four AUTH mechanism detection regexes contain overlapping whitespace sub-patterns that backtrack quadratically. A malicious or man-in-the-middle SMTP server can reply to EHLO with 250-AUTH, a long whitespace run and a non-matching token, blocking the Node.js event loop for tens of seconds to hours before authentication.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00367 30th percentileScored 2026-11-07

Fix Partial nodemailer (nodemailer): 10.0.13Red Hat: 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
nodemailer	nodemailer	3.0.0 to before 10.0.13	10.0.13	Patch available	CNA

nodemailer Vendornodemailer Affected 3.0.0 to before 10.0.13 Fixed in 10.0.13 Patch available CNA

Remediation

Update nodemailer to version 10.0.13. The sources list no fixed version for Self-service automation portal 2, and Red Hat's plan for it is none available.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Fix · CNA nodemailer (nodemailer) Fixed in 10.0.13

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

Release · 2026-10-14
nodemailer 10.0.13
2 records Highest priority Priority HIGH 2 HIGH
Other records, highest priority first
- TI-2026-74560 Nodemailer address parser passes illegal characters to SMTP envelopePriority HIGH 70
Show all 2 records →

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Product	Status	Plan or fix
Self-service automation portal 2	Affected	No fix yet

Not affected: 3 products

Red Hat Developer Hub 1
Red Hat Enterprise Linux 10
Red Hat Hardened Images

Timeline

2026-10-15 Threatist record created from CVE-2026-110869
2026-10-15 CISA SSVC decision points changed
2026-10-15 Priority changed: MEDIUM → HIGH
2026-10-16 Affected versions changed · Red Hat
2026-10-16 CVSS score added · Red Hat
2026-10-20 Affected versions changed · Red Hat
2026-10-27 Affected versions changed · Red Hat

References

Advisory 1

GitHub Security Advisory (GHSA-4ffr-jq9g-5ffx)

TI-2026-64856 nodemailer before 10.0.6 Denial of Service via addressparser CVSS 4.0HIGH 8.7
TI-2026-62452 Nodemailer before 9.1.0 Denial of Service via addressparser CVSS 4.0HIGH 8.7
TI-2026-61683 Nodemailer 9.1.0 through 10.0.4 Denial of Service via Quadratic Address Parsing CVSS 4.0HIGH 8.7
TI-2025-13566 Nodemailer: nodemailer: denial of service via crafted email address header CVSS 3.1HIGH 7.5
TI-2026-74560 Nodemailer address parser passes illegal characters to SMTP envelope CVSS 4.0MEDIUM 6.9
TI-2026-64855 Nodemailer before 10.0.9 Malformed Envelope Recipient via RFC 5322 Comment CVSS 4.0MEDIUM 6.9

See all 27 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences