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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 proxy resolves the ta

mediumCVSS 5.8CVE-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 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.

Details

Source
NVD Recent CVEs (US · database · site)
Severity
medium — CVSS 5.8
Published
2026-07-08
Last updated
2026-07-08
Exploitation
Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-55430

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2026-55430coverage & exploitation statusNVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

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