{"cve":"CVE-2026-55430","nvd":{"published":"2026-07-08T01:16:27.270","modified":"2026-07-08T19:43:14.500","status":"Analyzed","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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N","score":6.8},"cwes":["CWE-345","CWE-441"],"references":["https://github.com/coder/coder/pull/26204","https://github.com/coder/coder/releases/tag/v2.29.17","https://github.com/coder/coder/releases/tag/v2.32.7","https://github.com/coder/coder/releases/tag/v2.33.8","https://github.com/coder/coder/releases/tag/v2.34.2"],"products":["coder:coder"],"source":"nvd","synced_at":"2026-10-19T22:42:16.820116992+00:00"},"epss":{"cve":"CVE-2026-55430","score":0.00208,"percentile":0.1097,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-5g4w-3vw9-478w","url":"https://osv.dev/vulnerability/GHSA-5g4w-3vw9-478w","summary":"Coder's subdomain workspace app routing trusts unauthenticated X-Forwarded-Host header, enabling cross-app data access","modified":"2026-07-07T20:41:11.336853090Z","packages":[{"ecosystem":"Go","name":"github.com/coder/coder/v2","purl":"pkg:golang/github.com/coder/coder/v2","ranges":[">=2.34.0 <2.34.2"],"fixed":["2.34.2"]},{"ecosystem":"Go","name":"github.com/coder/coder/v2","purl":"pkg:golang/github.com/coder/coder/v2","ranges":[">=2.33.0 <2.33.8"],"fixed":["2.33.8"]},{"ecosystem":"Go","name":"github.com/coder/coder/v2","purl":"pkg:golang/github.com/coder/coder/v2","ranges":[">=2.30.0 <2.32.7"],"fixed":["2.32.7"]},{"ecosystem":"Go","name":"github.com/coder/coder/v2","purl":"pkg:golang/github.com/coder/coder/v2","ranges":["<2.29.17"],"fixed":["2.29.17"]}]},{"id":"GO-2026-5917","url":"https://osv.dev/vulnerability/GO-2026-5917","summary":"Coder's subdomain workspace app routing trusts unauthenticated X-Forwarded-Host header, enabling cross-app data access in github.com/coder/coder","modified":"2026-07-07T20:30:17.637359700Z","packages":[{"ecosystem":"Go","name":"github.com/coder/coder","purl":"pkg:golang/github.com/coder/coder","ranges":["all versions"],"fixed":[]},{"ecosystem":"Go","name":"github.com/coder/coder/v2","purl":"pkg:golang/github.com/coder/coder/v2","ranges":["<2.29.17",">=2.30.0 <2.32.7",">=2.33.0 <2.33.8",">=2.34.0 <2.34.2"],"fixed":["2.29.17","2.32.7","2.33.8","2.34.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}