CVE-2026-55438
published 2026-07-08CVE-2026-55438: 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…
PriorityP434medium6.8CVSS 3.1
AVNACLPRLUIRSCCHINAN
EPSS
0.22%
12.8th percentile
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.
Affected
11 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| coder | coder | < 2.29.17 | 2.29.17 |
| coder | coder | — | — |
| coder | coder | — | — |
| coder | coder | — | — |
| coder | coder | >= 2.30.0 < 2.32.7 | 2.32.7 |
| coder | coder | >= 2.33.0 < 2.33.8 | 2.33.8 |
| coder | coder | >= 2.34.0 < 2.34.2 | 2.34.2 |
| github.com | coder_coder_v2 | >= 0 < 2.29.17 | 2.29.17 |
| github.com | coder_coder_v2 | >= 2.30.0 < 2.32.7 | 2.32.7 |
| github.com | coder_coder_v2 | >= 2.33.0 < 2.33.8 | 2.33.8 |
| github.com | coder_coder_v2 | >= 2.34.0 < 2.34.2 | 2.34.2 |
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VulDB
coder Workspace App Proxy up to 2.29.16/2.32.6/2.33.7/2.34.1 cross-domain policy
vuldb·2026-07-08·CVSS 5.8
CVE-2026-55438 [MEDIUM] coder Workspace App Proxy up to 2.29.16/2.32.6/2.33.7/2.34.1 cross-domain policy
A vulnerability categorized as problematic has been discovered in coder Workspace App Proxy up to 2.29.16/2.32.6/2.33.7/2.34.1. Affected by this issue is some unknown functionality. Executing a manipulation can lead to permissive cross-domain policy with untrusted domains.
This vulnerability is tracked as CVE-2026-55438. The attack can be launched remotely. No exploit exists.
GHSA
Coder's workspace app CORS origin check can be bypassed via UUID-based subdomain spoofing
ghsa·2026-07-06
CVE-2026-55438 [MEDIUM] CWE-346 Coder's workspace app CORS origin check can be bypassed via UUID-based subdomain spoofing
Coder's workspace app CORS origin check can be bypassed via UUID-based subdomain spoofing
### Summary
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.
> **Note:** Practical exploitation requires subdomain app routing (wildcard hostname) enabled and a victim who visits the attacker's crafted app URL while authenticated.
### Impact
An authenticated user could craft a subdomain encoding their own workspace UUID and a victim's username. If the victim visited the attacker's URL, the attacker's JavaScript could issue crede
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
https://github.com/coder/coder/pull/26085https://github.com/coder/coder/pull/26086https://github.com/coder/coder/releases/tag/v2.29.17https://github.com/coder/coder/releases/tag/v2.32.7https://github.com/coder/coder/releases/tag/v2.33.8https://github.com/coder/coder/releases/tag/v2.34.2https://github.com/coder/coder/security/advisories/GHSA-5wg6-jmq2-53pw
2026-07-08
Published