CVE-2026-90776 Nodemailer 9.1.0 through 10.0.4 Denial of Service via Quadratic Address Parsing
Attackers can cause denial of service in Nodemailer by sending crafted email headers that trigger excessive CPU usage during address parsing.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-90776?
CVE-2026-90776 is a high-severity denial of service vulnerability in nodemailer, published on 13 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Nodemailer versions 9.1.0 through 10.0.4 contain a quadratic time complexity vulnerability in the addressparser component when parsing email addresses with RFC 5322 comments. Attackers can craft malicious email headers with comment-separated atoms to consume excessive CPU and block the Node.js event loop for several seconds, causing denial of service.
Weakness: CWE-407
Which versions are affected by CVE-2026-90776?
2 open source packages ship an affected version, including nodemailer.
| Package | Affected | Fixed in |
|---|---|---|
nodemailer npm | From 9.1.0 | 10.0.5 |
nodemailer npm | From 9.1.0 | 10.0.5 |
How do I fix CVE-2026-90776?
Upgrade nodemailer to 10.0.5 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-90776 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-90776 exists.
Sources
Also known as CLEANSTART-2026-GE40690, CLEANSTART-2026-WH49536, DEBIAN-CVE-2026-90776, ECHO-61a2-f0c6-30be, GHSA-prgh-xp8r-p3m5, MINI-5v8g-5w8f-jcr8 and 5 more.