CVE-2026-110871 nodemailer CVE debrief

Who should care

Defenders responsible for Node.js applications using Nodemailer versions 3.0.0 before 10.0.10 should assess exposure and prioritize updating to version 10.0.10 or later to prevent potential denial-of-service attacks.

Why it matters

CVE-2026-110871 is a high-severity denial-of-service vulnerability affecting Nodemailer versions 3.0.0 before 10.0.10. Defenders should prioritize verifying and updating Nodemailer to prevent potential denial-of-service attacks. The vulnerability allows attackers to exhaust CPU resources by supplying large recipient lists or long headers.

• Potential denial-of-service attacks through CPU exhaustion
• Verification of Nodemailer version and update to 10.0.10 or later
• Monitoring for large recipient lists and long headers in email messages

Technical summary

The vulnerability is caused by quadratic DKIM header unfolding in the MessageParser.parseHeaders function of Nodemailer versions 3.0.0 before 10.0.10. This allows attackers to exhaust CPU resources by supplying large recipient lists or long headers that fold into tens of thousands of continuation lines, blocking the Node.js event loop during DKIM signing. The affected product context indicates that Nodemailer versions 3.0.0 before 10.0.10 are vulnerable. Defenders should prioritize verifying and updating Nodemailer to version 10.0.10 or later to prevent potential denial-of-service attacks. The technical framing of this vulnerability highlights the importance of reviewing and limiting large recipient lists and

Defensive priority

Defenders should prioritize verifying and updating Nodemailer to version 10.0.10 or later to prevent potential denial-of-service attacks.

Recommended defensive actions

• Verify Nodemailer version and update to 10.0.10 or later if necessary
• Review and limit large recipient lists and long headers in email messages
• Monitor for potential denial-of-service attacks through CPU exhaustion
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, including its cause, affected versions, and potential impact. However, there is limited information on actual exploitation or victim impact.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.