{"id":"CVE-2026-72817","aliases":["GHSA-9g5q-2w5x-hmxf","GO-2026-5775"],"url":"https://o3.security/vulnerability/CVE-2026-72817","summary":"go-chi chi 0.9.0 before 5.3.0 IP Spoofing via X-Forwarded-For","details":"go-chi/chi versions 0.9.0 before 5.3.0 contains an IP spoofing vulnerability in the RealIP middleware, which resolves the request source IP (Request.RemoteAddr) using the first IP in the X-Forwarded-For header without validating trusted proxies. A malicious client can prepend a forged IP as the first value of the X-Forwarded-For header to spoof the request source IP, potentially bypassing access controls or falsifying request logs.","published":"2026-08-14T11:35:28.824Z","modified":"2026-08-28T17:40:53.294360964Z","cvss":null,"epss":{"score":0.0015,"percentile":0.04495,"asOf":"2026-09-07"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/go-chi/chi/middleware","fixedVersion":null},{"ecosystem":"Go","name":"github.com/go-chi/chi/v2/middleware","fixedVersion":null},{"ecosystem":"Go","name":"github.com/go-chi/chi/v3/middleware","fixedVersion":null},{"ecosystem":"Go","name":"github.com/go-chi/chi/v4/middleware","fixedVersion":null},{"ecosystem":"Go","name":"github.com/go-chi/chi/v5/middleware","fixedVersion":"5.3.0"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72817.json"},{"type":"ADVISORY","url":"https://github.com/go-chi/chi/security/advisories/GHSA-9g5q-2w5x-hmxf"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72817"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/go-chi-chi-before-ip-spoofing-via-x-forwarded-for"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-28T17:40:53.294360964Z"}}