CVSS 3.1
6.8 mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:NCVE-2026-55430
Medium (6.8) in coder coder. EPSS 0.2% chance of exploitation in the next 30 days. Fixed in github.com/coder/coder/v2 2.29.17, 2.32.7, 2.33.8.
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.
Severity
- EPSS
- 0.2% chance of exploitation in the next 30 days; higher than 10% of CVEs (scores of 2026-10-31)
- CWEs
- CWE-345, CWE-441
- Published
- Modified
- Record from
- the NVD, synced
Affected
- coder:coder
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-5g4w-3vw9-478w | Go | github.com/coder/coder/v2 | >=2.34.0 <2.34.2 | 2.34.2 |
| GHSA-5g4w-3vw9-478w | Go | github.com/coder/coder/v2 | >=2.33.0 <2.33.8 | 2.33.8 |
| GHSA-5g4w-3vw9-478w | Go | github.com/coder/coder/v2 | >=2.30.0 <2.32.7 | 2.32.7 |
| GHSA-5g4w-3vw9-478w | Go | github.com/coder/coder/v2 | <2.29.17 | 2.29.17 |
| GO-2026-5917 | Go | github.com/coder/coder | all versions | no fix published |
| GO-2026-5917 | Go | github.com/coder/coder/v2 | <2.29.17 >=2.30.0 <2.32.7 >=2.33.0 <2.33.8 >=2.34.0 <2.34.2 | 2.29.17, 2.32.7, 2.33.8, 2.34.2 |