CVE-2026-55430

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.

CVSS 3.1

6.8 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N

EPSS

0.21% probability · 11th percentile

Public exploits

None in Exploit-DB

CISA KEV

Not listed

Weakness

CWE-345, CWE-441

Affected

coder/coder

Source

security-advisories@github.com

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.