CVE-2026-55431
Coder's session token leaked to arbitrary hosts via `coder open app` for external workspace apps
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.
INFO
Published Date :
July 8, 2026, 1:16 a.m.
Last Modified :
July 8, 2026, 7:42 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Coder to version 2.29.7 or later.
- Update Coder to version 2.32.7 or later.
- Update Coder to version 2.33.8 or later.
- Update Coder to version 2.34.2 or later.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-55431.
| URL | Resource |
|---|---|
| https://github.com/coder/coder/pull/26146 | Issue Tracking Patch |
| https://github.com/coder/coder/releases/tag/v2.29.17 | Release Notes |
| https://github.com/coder/coder/releases/tag/v2.32.7 | Release Notes |
| https://github.com/coder/coder/releases/tag/v2.33.8 | Release Notes |
| https://github.com/coder/coder/releases/tag/v2.34.2 | Release Notes |
| https://github.com/coder/coder/security/advisories/GHSA-v54h-cp2w-9x4g | Patch Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-55431 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-55431
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-55431 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-55431 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jul. 08, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Added CPE Configuration OR *cpe:2.3:a:coder:coder:*:*:*:*:*:go:*:* versions up to (excluding) 2.29.17 *cpe:2.3:a:coder:coder:*:*:*:*:*:go:*:* versions from (including) 2.30.0 up to (excluding) 2.32.7 *cpe:2.3:a:coder:coder:*:*:*:*:*:go:*:* versions from (including) 2.33.0 up to (excluding) 2.33.8 *cpe:2.3:a:coder:coder:*:*:*:*:*:go:*:* versions from (including) 2.34.0 up to (excluding) 2.34.2 Added Reference Type GitHub, Inc.: https://github.com/coder/coder/pull/26146 Types: Issue Tracking, Patch Added Reference Type GitHub, Inc.: https://github.com/coder/coder/releases/tag/v2.29.17 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/coder/coder/releases/tag/v2.32.7 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/coder/coder/releases/tag/v2.33.8 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/coder/coder/releases/tag/v2.34.2 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/coder/coder/security/advisories/GHSA-v54h-cp2w-9x4g Types: Patch, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 08, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-55431', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-07-08T13:56:53.370657Z'} -
New CVE Received by [email protected]
Jul. 08, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'coder', 'product': 'coder', 'versions': [{'status': 'affected', 'version': '>= 2.34.0, < 2.34.2'}, {'status': 'affected', 'version': '>= 2.33.0, < 2.33.8'}, {'status': 'affected', 'version': '>= 2.30.0, < 2.32.7'}, {'status': 'affected', 'version': '< 2.29.17'}]}] Added 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. Added CVSS V3.1 AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N Added CWE CWE-601 Added CWE CWE-522 Added Reference https://github.com/coder/coder/pull/26146 Added Reference https://github.com/coder/coder/releases/tag/v2.29.17 Added Reference https://github.com/coder/coder/releases/tag/v2.32.7 Added Reference https://github.com/coder/coder/releases/tag/v2.33.8 Added Reference https://github.com/coder/coder/releases/tag/v2.34.2 Added Reference https://github.com/coder/coder/security/advisories/GHSA-v54h-cp2w-9x4g