# CVE-2026-92596: Nodemailer before 9.1.0 Denial of Service via addressparser

> Remote attackers can cause denial of service in Nodemailer by sending crafted email addresses, blocking the Node.js event loop and consuming CPU resources.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** CLEANSTART-2026-DX95519, CLEANSTART-2026-NH33763, CLEANSTART-2026-QL18183, CLSA-2026-1791795466, CLSA-2026-1791806342, CLSA-2026-1791814986, DEBIAN-CVE-2026-92596, ECHO-647b-63be-59c8, GHSA-2x7j-588g-ccc2, GHSA-v554-hhrr-96v5, MINI-2834-8w3m-3r4g, MINI-2gfq-rgrf-9vwr, MINI-535v-9qr7-5fff, MINI-53wr-qp74-c4vm, MINI-59v6-f3j4-hjm5, MINI-67m2-mf9x-qwgr, MINI-74r6-xf6p-vxqx, MINI-gjr9-qg8h-fhm3, MINI-hm33-4x74-3385, MINI-hw5p-54hv-94hw, MINI-jwcx-r2gh-83v7, MINI-m68g-8hmj-qxhf, MINI-pf37-47m5-xf54, MINI-pfhm-hv4p-vp57, MINI-rxc4-6jw4-3m7f, MINI-x28w-jvjj-8mc7, ROOT-APP-NPM-GHSA-2x7j-588g-ccc2, UBUNTU-CVE-2026-92596

## What is CVE-2026-92596?

CVE-2026-92596 is a high-severity denial of service vulnerability in nodemailer, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Nodemailer before 9.1.0 contains a quadratic time complexity vulnerability in the addressparser component that allows remote attackers to cause denial of service by supplying a crafted comma-separated address list. Attackers can send a single email with a large number of addresses to block the Node.js event loop for extended periods, consuming 100% CPU and freezing the process.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-92596?

2 open source packages ship an affected version, including nodemailer.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `nodemailer` | npm | All versions | 9.1.0 |
| `nodemailer` | npm | All versions | 9.1.0 |

## How do I fix CVE-2026-92596?

Upgrade nodemailer to 9.1.0 or later.

## Is CVE-2026-92596 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-92596 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-92596 and fix it if it is affected.

What it is: CVE-2026-92596 is a high-severity denial of service vulnerability in nodemailer, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-92596 exists.

Affected packages and fixed versions:
- nodemailer (npm): affected all versions; fixed in 9.1.0
- nodemailer (npm): affected all versions; fixed in 9.1.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-92596/ (Markdown: https://insights.sbomify.com/CVE-2026-92596/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-92596
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-92596
- OSV: https://osv.dev/vulnerability/CVE-2026-92596

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-92596/
Summaries are generated and may contain mistakes; the official description above is the record.