---
id: CVE-2026-55427
aliases:
  - GHSA-mcqq-fqgf-rxwm
title: >-
  Coder vulnerable to SSH config injection via unsanitized server-supplied
  values in `coder config-ssh`
summary: >-
  Coder vulnerable to SSH config injection via unsanitized server-supplied
  values in `coder config-ssh`
severity: high
cvss: 8.3
cwe:
  - CWE-74
  - CWE-78
vendor: coder
product: github.com/coder/coder/v2
ecosystem: go
affected:
  - 'github.com/coder/coder/v2 >= 2.34.0, < 2.34.2'
  - 'github.com/coder/coder/v2 >= 2.33.0, < 2.33.8'
  - 'github.com/coder/coder/v2 >= 2.30.0, < 2.32.7'
  - github.com/coder/coder/v2 < 2.29.17
patched:
  - github.com/coder/coder/v2 2.34.2
  - github.com/coder/coder/v2 2.33.8
  - github.com/coder/coder/v2 2.32.7
  - github.com/coder/coder/v2 2.29.17
published: '2026-07-06'
updated: '2026-07-06'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-mcqq-fqgf-rxwm'
references:
  - url: 'https://github.com/coder/coder/security/advisories/GHSA-mcqq-fqgf-rxwm'
  - url: 'https://github.com/coder/coder/pull/26154'
  - url: 'https://github.com/advisories/GHSA-mcqq-fqgf-rxwm'
tags:
  - ghsa
  - go
ingestedAt: '2026-07-06T21:45:52.972Z'
epss: 0.00466
epssPercentile: 0.37647
---

## Overview

### Summary

`coder config-ssh` wrote server-supplied SSH settings (`HostnameSuffix`, `SSHConfigOptions`) into the user's `~/.ssh/config` without sanitizing embedded newlines or restricting directives so a malicious or compromised Coder server could inject arbitrary SSH configuration.

> **Note:** Practical exploitation requires control of the server-supplied values through a malicious or compromised deployment, a man-in-the-middle position or admin access to the `HostnameSuffix` and `SSHConfigOptions` settings.

### Impact

A server administrator or an attacker who controlled the server, could inject a directive such as `ProxyCommand` and achieve arbitrary code execution on any developer workstation that ran `coder config-ssh`. Injected commands ran with the local user's privileges and applied to all SSH connections, not just Coder workspaces.

### Patches

The fix validates `HostnameSuffix` and `SSHConfigOptions` against a strict character set that rejects newlines and other control characters.

The fix was backported to all supported release lines:

| Release line | Patched version |
|---|---|
| 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) |
| 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) |
| 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) |
| 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) |

### Workarounds

Inspect `coder config-ssh --dry-run` output before applying changes.

### Resources

- Fix: #26154

### Credits

Coder would like to thank Anthropic's Security Team (ANT-2026-22437) for independently disclosing this issue!

## Affected packages

- `github.com/coder/coder/v2 >= 2.34.0, < 2.34.2`
- `github.com/coder/coder/v2 >= 2.33.0, < 2.33.8`
- `github.com/coder/coder/v2 >= 2.30.0, < 2.32.7`
- `github.com/coder/coder/v2 < 2.29.17`

## Remediation

Upgrade to a patched release:

- `github.com/coder/coder/v2 2.34.2`
- `github.com/coder/coder/v2 2.33.8`
- `github.com/coder/coder/v2 2.32.7`
- `github.com/coder/coder/v2 2.29.17`