Nodemailer: Quadratic backtracking in the addressparser free-text fallback allows remote denial of service — GHSA-V53P-9FQP-M79J

Summary

### Summary When `addressparser` finds no address by its strict reading, it falls back to pulling one out of the free text with `/\s*\b[^@\s]+@[^\s]+\b\s*/`. That pattern backtracks quadratically: `[^@\s]+` is retried from every offset and rescans the run to the next `@` each time. A single header value holding a long whitespace-free run with no usable `@` blocks the Node.js event loop for tens of seconds. It is…

Timeline

Published by source

2026-09-29

Risk context

• Reported severity or threat level: high.
• Reported CVSS score: 7.5 out of 10.
• Review exposure for the affected product or family: npm: nodemailer.

Product

npm: nodemailer

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source

Evidence and provenance

Canonical advisory ID

GHSA-V53P-9FQP-M79J

Source

GitHub

Vendor

GitHub

Published by source

2026-09-29

Last source activity

2026-09-29

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.