CVE-2026-55427: coder Injection — Fix

Description

Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, `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. 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. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 validates `HostnameSuffix` and `SSHConfigOptions` against a strict character set that rejects newlines and other control characters. As a workaround, inspect `coder config-ssh --dry-run` output before applying changes.

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CVSS v3.1 Score

8.3

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0047

Probability of exploitation

0.38%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-74 CWE-74

CWE-78 OS Command Injection

Affected Products

Vendor	Product	Versions
coder	coder	< 2.29.17
coder	coder	2.30.0 — 2.32.7
coder	coder	2.33.0 — 2.33.8
coder	coder	2.34.0 — 2.34.2

References

Advisories & Patches

https://github.com/coder/coder/pull/26154 https://github.com/coder/coder/security/advisories/GHSA-mcqq-fqgf-rxwm

Other References

https://github.com/coder/coder/releases/tag/v2.29.17 https://github.com/coder/coder/releases/tag/v2.32.7 https://github.com/coder/coder/releases/tag/v2.33.8 https://github.com/coder/coder/releases/tag/v2.34.2

Frequently Asked Questions

What is CVE-2026-55427? +

Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, `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. 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. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 validates `HostnameSuffix` and `SSHConfigOptions` against a strict character set that rejects newlines and other control characters. As a workaround, inspect `coder config-ssh --dry-run` output before applying changes. It has a CVSS v3.1 base score of 8.3 (HIGH).

How severe is CVE-2026-55427? +

CVE-2026-55427 has a CVSS v3.1 score of 8.3 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0047, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-55427? +

CVE-2026-55427 affects products from coder, specifically: coder. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-55427? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-55427