CVE-2026-55430: 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…

PriorityP334medium6.8CVSS 3.1

AVNACLPRLUIRSCCHINAN

EPSS

0.21%

11.3th percentile

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.

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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