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, the workspace app proxy resolves the target app from `httpapi.RequestHost()` which prefers the `X-Forwarded-Host` header over the real `Host` header. No middleware strips `X-Forwarded-Host` before routing and the header is not browser-forbidden so client-side JavaScript can set it on `fetch()` calls. Practical exploitation requires subdomain app routing (wildcard hostname) enabled, a victim who visits the attacker's shared app and a deployment whose upstream proxy does not strip `X-Forwarded-Host`. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 trusts `X-Forwarded-Host` only from configured trusted proxies and otherwise resolves the routing host from the verified request host. As a workaround, place an upstream reverse proxy that strips or overwrites `X-Forwarded-Host` on untrusted requests.
Advisories
| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-5g4w-3vw9-478w | Coder's subdomain workspace app routing trusts unauthenticated X-Forwarded-Host header, enabling cross-app data access |
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Wed, 08 Jul 2026 02:45:00 +0000
| Type | Values Removed | Values Added |
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| First Time appeared |
Coder
Coder coder |
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| Vendors & Products |
Coder
Coder coder |
Wed, 08 Jul 2026 01:00:00 +0000
| Type | Values Removed | Values 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, the workspace app proxy resolves the target app from `httpapi.RequestHost()` which prefers the `X-Forwarded-Host` header over the real `Host` header. No middleware strips `X-Forwarded-Host` before routing and the header is not browser-forbidden so client-side JavaScript can set it on `fetch()` calls. Practical exploitation requires subdomain app routing (wildcard hostname) enabled, a victim who visits the attacker's shared app and a deployment whose upstream proxy does not strip `X-Forwarded-Host`. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 trusts `X-Forwarded-Host` only from configured trusted proxies and otherwise resolves the routing host from the verified request host. As a workaround, place an upstream reverse proxy that strips or overwrites `X-Forwarded-Host` on untrusted requests. | |
| Title | Coder's subdomain workspace app routing trusts unauthenticated X-Forwarded-Host header, enabling cross-app data access | |
| Weaknesses | CWE-345 CWE-441 |
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| References |
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| Metrics |
cvssV3_1
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Projects
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-07-08T00:03:29.728Z
Reserved: 2026-06-16T21:59:57.017Z
Link: CVE-2026-55430
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OpenCVE Enrichment
Updated: 2026-07-08T15:45:03Z
Github GHSA