CVE-2026-55438
Coder's workspace app CORS origin check can be bypassed via UUID-based subdomain spoofing
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.
INFO
Published Date :
July 8, 2026, 1:16 a.m.
Last Modified :
July 8, 2026, 1:16 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-55438
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Coder to version 2.29.17 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-2026-55438.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-55438 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-2026-55438
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-2026-55438 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-55438 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.
-
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 2.29.17, 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. Added CVSS V3.1 AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:N/A:N Added CWE CWE-346 Added Reference https://github.com/coder/coder/pull/26085 Added Reference https://github.com/coder/coder/pull/26086 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-5wg6-jmq2-53pw