CVE-2026-55430
Last modified
CVE-2026-55430 is a medium-severity vulnerability rated 6.8/10 on the CVSS scale. 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. EPSS estimates a 0.20% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Coder | Coder | < 2.29.17 |
| Coder | Coder | >= 2.30.0, < 2.32.7 |
| Coder | Coder | >= 2.33.0, < 2.33.8 |
| Coder | Coder | >= 2.34.0, < 2.34.2 |
References
- https://github.com/coder/coder/pull/26204Issue Tracking, Patch
- https://github.com/coder/coder/releases/tag/v2.29.17Release Notes
- https://github.com/coder/coder/releases/tag/v2.32.7Release Notes
- https://github.com/coder/coder/releases/tag/v2.33.8Release Notes
- https://github.com/coder/coder/releases/tag/v2.34.2Release Notes
- https://github.com/coder/coder/security/advisories/GHSA-5g4w-3vw9-478wPatch, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
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How Strix Helps
- Same Subject, Wrong User: A Cross-Issuer Account Takeover in n8nStrix found an identity-binding bug in n8n's token-exchange flow enabling account takeover.
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