# Netty has SMTP Command Injection Vulnerability that Allows Email Forgery

Advisory record · `GHSA-jq43-27x9-3v86`

- **Identifiers:** `GHSA-jq43-27x9-3v86` · `CVE-2025-59419`
- **State:** Confirmed
- **Severity:** CVSS 5.5 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-78](https://cwe.mitre.org/data/definitions/78.html) · [CWE-93](https://cwe.mitre.org/data/definitions/93.html)
- **Tags:** [Command injection](https://agentprime.io/advisories/tag/command-injection.md) · [Other injection](https://agentprime.io/advisories/tag/injection.md)
- **Published:** 15 Oct 2025
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 15 Oct 2025, 17:12 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `io.netty:netty-codec-smtp` (Maven): affected `>=4.2.0.Alpha1, <4.2.7.Final || <4.1.128.Final`; fixed in `4.2.7.Final`, `4.1.128.Final`

## Machine-written summary

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

> The netty-codec-smtp package (io.netty:netty-codec-smtp) from 4.2.0.Alpha1 before 4.2.7.Final, and from earlier 4.1 releases before 4.1.128.Final, does not reject carriage return and line feed characters in SMTP command parameters such as recipients. A remote attacker who can control those parameters may inject additional SMTP commands and send forged emails from the server. Upgrade to 4.2.7.Final or 4.1.128.Final, or later.

Written 2 Nov 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

- 5.5 Medium, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.016, the 75th percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:17 UTC: First seen by agentprime
- 31 Oct 2026, 14:17 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-jq43-27x9-3v86)

## Sources

- [GitHub Advisory Database: GHSA-jq43-27x9-3v86](https://github.com/advisories/GHSA-jq43-27x9-3v86)
- [OSV: GHSA-jq43-27x9-3v86](https://osv.dev/vulnerability/GHSA-jq43-27x9-3v86)
- <https://github.com/netty/netty/security/advisories/GHSA-jq43-27x9-3v86>
- <https://nvd.nist.gov/vuln/detail/CVE-2025-59419>
- <https://github.com/netty/netty/commit/1782e8c2060a244c4d4e6f9d9112d5517ca05120>
- <https://github.com/netty/netty/commit/2b3fddd3339cde1601f622b9ce5e54c39f24c3f9>
- <https://gist.github.com/DepthFirstDisclosures/ddacca28cb94b48fa8ab998cef59ed8c>
- <https://github.com/netty/netty>
- <https://www.depthfirst.com/post/our-ai-agent-found-a-netty-zero-day-that-bypasses-email-authentication-the-story-of-cve-2025-59419>

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-jq43-27x9-3v86>, 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-jq43-27x9-3v86/>. Everything for agents: <https://agentprime.io/llms.txt>.