# Nodemailer addressparser: O(n^2) on comment-joined addresses enables a remote DoS (reachable via mailparser)

Advisory record · `GHSA-prgh-xp8r-p3m5`

- **Identifiers:** `GHSA-prgh-xp8r-p3m5` · `CVE-2026-90776`
- **State:** Confirmed
- **Severity:** CVSS 8.7 High
- **Critical:** No
- **Weakness (CWE):** [CWE-400](https://cwe.mitre.org/data/definitions/400.html) · [CWE-407](https://cwe.mitre.org/data/definitions/407.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 30 Sept 2026
- **Updated:** 5 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 30 Sept 2026, 14:41 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `nodemailer` (npm): affected `>=9.1.0, <10.0.5`; fixed in `10.0.5`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Nodemailer versions 9.1.0 up to 10.0.5 (excluding 10.0.5) are affected by a quadratic-time parsing flaw in the addressparser module, which mailparser also uses on inbound email headers. A remote attacker can send one crafted email with a very long comment-joined address, requiring no authentication, to block the Node.js event loop for several seconds and stall a service that parses mail. The fix is to upgrade nodemailer to version 10.0.5.

Written 31 Oct 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 8.7 High, CVSS 4.0: `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`, from CNA (VulnCheck)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0068, the 53rd percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 13:34 UTC: First seen by agentprime
- 31 Oct 2026, 13:34 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-prgh-xp8r-p3m5)

## Sources

- [GitHub Advisory Database: GHSA-prgh-xp8r-p3m5](https://github.com/advisories/GHSA-prgh-xp8r-p3m5)
- [OSV: GHSA-prgh-xp8r-p3m5](https://osv.dev/vulnerability/GHSA-prgh-xp8r-p3m5)
- <https://github.com/nodemailer/nodemailer/security/advisories/GHSA-prgh-xp8r-p3m5>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-90776>
- <https://github.com/nodemailer/nodemailer/commit/c07f17518d25aca8ab2ad66968dcbca538c24b89>
- <https://github.com/nodemailer/nodemailer>
- <https://github.com/nodemailer/nodemailer/releases/tag/v10.0.5>
- <https://www.vulncheck.com/advisories/nodemailer-9.1.0-through-10.0.4-denial-of-service-via-quadratic-address-parsing>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-prgh-xp8r-p3m5>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-prgh-xp8r-p3m5/>. Everything for agents: <https://agentprime.io/llms.txt>.