CVE-2026-55431

Vulnerability 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 open app` opens external workspace-app URLs without validating the scheme or host. When an external app URL contains the `$SESSION_TOKEN` placeholder the CLI replaces it with the user's real session token before handing the URL to the OS open handler. Practical exploitation requires the victim to run `coder open app` against a workspace whose external app definition the attacker controls. Only a malicious template author can control external app URLs. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 applies a URL-scheme allowlist in the CLI and limits `$SESSION_TOKEN` substitution to trusted destinations like the web frontend. As a workaround, avoid running `coder open app` for untrusted workspaces.

CVSS Score

Affected Products

Related Weaknesses (CWE)

References

• https://github.com/coder/coder/pull/26146Issue 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-v54h-cp2w-9x4gPatchVendor Advisory