CVE-2026-55438

Vulnerability Description

Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.17, 2.32.7, 2.33.8, and 2.34.2, Coder's subdomain-based workspace app proxy allowed the same-owner CORS check to be bypassed. When a workspace-name subdomain segment parsed as a UUID, the workspace was resolved by ID without confirming the URL's username matched the real owner, while the CORS middleware trusted the unverified username in the hostname. Practical exploitation requires subdomain app routing (wildcard hostname) enabled and a victim who visits the attacker's crafted app URL while authenticated. The fix in versions 2.29.17, 2.32.7, 2.33.8, and 2.34.2 validates the subdomain username against the resolved workspace's actual owner and bases the same-owner CORS decision on the authoritative owner identity. No known workarounds are available.

CVSS Score

Affected Products

Related Weaknesses (CWE)

References

• https://github.com/coder/coder/pull/26085Issue TrackingPatch
• https://github.com/coder/coder/pull/26086Issue TrackingPatch
• https://github.com/coder/coder/releases/tag/v2.29.17Release Notes
• https://github.com/coder/coder/releases/tag/v2.32.7Release Notes
• https://github.com/coder/coder/releases/tag/v2.33.8Release Notes
• https://github.com/coder/coder/releases/tag/v2.34.2Release Notes
• https://github.com/coder/coder/security/advisories/GHSA-5wg6-jmq2-53pwPatchVendor Advisory