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TI-2026-74561 Aliases CVE-2026-110871GHSA-39m8-27wv-hr27

Quadratic header unfolding in Nodemailer enables denial of service

Priority MEDIUM 64CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
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: 3 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.

Summary

Nodemailer from 3.0.0 before 10.0.10 contains a quadratic header unfolding flaw in MessageParser.parseHeaders (CWE-407). A remote user with low privileges can send large recipient lists or long headers that fold into tens of thousands of continuation lines, exhausting CPU and blocking the Node.js event loop during DKIM signing.

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

Description from the CNA

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00381 32nd percentileScored 2026-11-07
Fix Partial nodemailer (nodemailer): 10.0.10nodemailer (npm): 10.0.10Red Hat: 3 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

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

Affected products

VendorProductAffected versionsFixed inStatusSource
nodemailernodemailer3.0.0 to before 10.0.1010.0.10Patch availableCNA
—nodemailer (npm)3.0.0 to before 10.0.1010.0.10Patch availableGHSA-39m8-27wv-hr27
  • nodemailer Vendornodemailer Affected 3.0.0 to before 10.0.10 Fixed in 10.0.10 Patch available CNA
  • nodemailer (npm) Vendor— Affected 3.0.0 to before 10.0.10 Fixed in 10.0.10 Patch available GHSA-39m8-27wv-hr27

Remediation

Upgrade Nodemailer to version 10.0.10, which is the fixed version for the nodemailer package on npm. The sources list no fixed version for Red Hat Developer Hub 1, Red Hat Enterprise Linux 10 or Self-service automation portal 2.

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

  • Fix · CNA nodemailer (nodemailer) Fixed in 10.0.10
  • Fix · GHSA-39m8-27wv-hr27 nodemailer (npm) Fixed in 10.0.10 Advisory →

Fixed in the same release

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

  • Release ·

    nodemailer 10.0.10

    2 records Highest priority Priority HIGH 1 HIGH, 1 MEDIUM

    Other records, highest priority first

    • TI-2026-74562 Denial of service in Nodemailer SMTP reply parsingPriority HIGH 69
    Show all 2 records →

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Red Hat Developer Hub 1AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 10AffectedNo fix yet: Fix deferred
Self-service automation portal 2AffectedNo fix yet: Fix deferred
Not affected: 1 product
  • Red Hat Hardened Images

Timeline

  1. 2026-10-15 Threatist record created from CVE-2026-110871
  2. 2026-10-16 Priority changed: MEDIUM → LOW
  3. 2026-10-16 Affected versions changed · Red Hat
  4. 2026-10-16 CVSS score added · Red Hat
  5. 2026-10-20 CISA SSVC decision points changed
  6. 2026-10-20 Priority changed: LOW → MEDIUM
  7. 2026-10-22 Alias added: GHSA-39m8-27wv-hr27
  8. 2026-10-22 Fix available: npm/[email protected] · GHSA-39m8-27wv-hr27
  9. 2026-10-22 CVSS score added · GHSA-39m8-27wv-hr27
  10. 2026-10-22 Weakness changed · GHSA-39m8-27wv-hr27
  11. 2026-10-22 5 new references · GHSA-39m8-27wv-hr27
  12. 2026-10-27 Affected versions changed · Red Hat

References

Advisory 2

Other 3

  • TI-2026-74559 ReDoS in Nodemailer SMTP AUTH mechanism detection regexes CVSS 4.0HIGH 8.7
  • 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
See all 27 →

Sources

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