CVE-2026-55431
Coder's session token leaked to arbitrary hosts via `coder open app` for external workspace apps
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/coder/coder/v2 | >= 2.34.0, < 2.34.2 | 2.34.2 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Coder | Coder | before 2.29.17 from 2.30.0 before 2.32.7 from 2.33.0 before 2.33.8 from 2.34.0 before 2.34.2 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-v54h-cp2w-9x4g
- https://github.com/coder/coder/security/advisories/GHSA-v54h-cp2w-9x4g
- https://github.com/coder/coder/pull/26146
- 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