# CVE-2026-90776: Nodemailer quadratic time complexity in address parser

Source: https://junglewise.ai/threats/cve-2026-90776-nodemailer-quadratic-time-complexity-in-address-parser  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-13. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-90776 · Severity: high · CVSS 7.5 · Published 2026-09-13

Nodemailer is a popular Node.js library for sending emails. Versions 9.1.0 through 10.0.4 contain a performance flaw in email address parsing that allows attackers to crash or severely slow down applications by sending specially crafted email headers, causing service disruption and potential denial of service attacks.

Technologies: [Nodemailer](https://junglewise.ai/threats/technologies/nodemailer), [nodemailer (npm)](https://junglewise.ai/threats/technologies/npm-nodemailer). Vendors: [Nodemailer](https://junglewise.ai/threats/vendors/nodemailer), [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-90776 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-90776 being exploited in the wild.

**How severe is CVE-2026-90776?** High severity, with a CVSS score of 7.5, published 13 September 2026.

**Which products and versions are affected?** Nodemailer 9.1.0 through 10.0.4; nodemailer (npm) SEMVER:introduced=9.1.0,fixed=10.0.5.

**Is there a fix for CVE-2026-90776?** Yes. nodemailer (npm): upgrade to 10.0.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-90776 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-90776?** Check whether you run Nodemailer or nodemailer (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- nodemailer (npm): upgrade to 10.0.5 or later

  ```sh
  npm install nodemailer@10.0.5
  ```


## Technical details

The vulnerability is a quadratic time complexity (ReDoS-like) flaw in the addressparser component when processing RFC 5322 comments in email addresses. An attacker can craft malicious email headers with nested or repeated comment-separated atoms that trigger the quadratic parsing behavior, consuming excessive CPU and blocking the Node.js event loop for several seconds. This is a network-accessible vulnerability triggered during email address parsing. The vulnerability affects Nodemailer versions 9.1.0 through 10.0.4; users should upgrade to a patched version when available.

## Affected products

- Nodemailer Nodemailer 9.1.0 through 10.0.4

## Identifiers

- CVE-2026-90776
- GHSA-prgh-xp8r-p3m5

## Timeline

- 2026-09-13: disclosed

## References

- [https://github.com/nodemailer/nodemailer](https://github.com/nodemailer/nodemailer)
- [https://github.com/nodemailer/nodemailer/blob/v10.0.4/src/addressparser/index.ts](https://github.com/nodemailer/nodemailer/blob/v10.0.4/src/addressparser/index.ts)

## Related threats

- [Nodemailer address parsing bypass in addressparser](https://junglewise.ai/threats/cve-2026-125755-nodemailer-3-0-0-before-10-4-1-contains-an-address-parsing-flaw)
- [Nodemailer address parsing bypass in nested RFC 5322 comments](https://junglewise.ai/threats/cve-2026-121424-nodemailer-from-3-0-0-before-10-1-4-contains-an-address-parsing)
- [Nodemailer addressparser RFC 5322 comment parsing bypass](https://junglewise.ai/threats/nodemailer-a-nested-comment-ends-early-in-addressparser-releasing-the-4e80613c)
- [Nodemailer addressparser group terminator bypass in quoted strings](https://junglewise.ai/threats/nodemailer-a-inside-a-quoted-string-or-comment-ends-an-address-group-b8b045f9)
- [Nodemailer addressparser angle-addr parsing bypass](https://junglewise.ai/threats/nodemailer-a-inside-a-quoted-local-part-ends-an-angle-addr-early-in-28663cfb)