Open Redirect in Coder

CVE-2026-55431

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.7 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.003 (24.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 24.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-55431: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

  • Coder — versions >= 2.34.0, < 2.34.2, >= 2.33.0, < 2.33.8, >= 2.30.0, < 2.32.7

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-55431?
CVE-2026-55431 is a high-severity vulnerability in Coder, classified under Insufficiently Protected Credentials. CVSS score: 7.7/10. Published 2026-07-08.
How severe is CVE-2026-55431?
High severity. CVSS v3 base score is 7.7 out of 10.