go-chi chi versions >= 5.2.1 and before 5.3.0 contain an IP spoofing vulnerability in the RealIP middleware, which blindly trusts the first (leftmost) value of the X-Forwarded-For HTTP header. A remote attacker can bypass IP-based access control lists and rate-limiting mechanisms, and forge log entries, by supplying a spoofed IP address in the X-Forwarded-For header. The issue is fixed in version 5.3.0.

go-chi chi versions >= 5.2.1 and before 5.3.0 contain an IP spoofing vulnerability in the RealIP middleware, which blindly trusts the first (leftmost) value of the X-Forwarded-For HTTP header. A remote attacker can bypass IP-based access control lists and rate-limiting mechanisms, and forge log entries, by supplying a spoofed IP address in the X-Forwarded-For header. The issue is fixed in version 5.3.0.

cloudflared-2026.8.2-1.1 on GA media

github.com/go-chi/chi/middleware: go-chi chi: IP spoofing via X-Forwarded-For header allows bypass of access controls github.com/go-chi/chi: go-chi/chi: IP Spoofing via RealIP Middleware allows bypassing access controls github.com/go-chi/chi/middleware: go-chi/chi: IP spoofing via X-Forwarded-For header manipulation

Affected: Ubuntu:22.04:LTS: golang-github-go-chi-chi, Ubuntu:24.04:LTS: golang-github-go-chi-chi, Ubuntu:26.04:LTS: golang-github-go-chi-chi

go-chi chi versions >= 5.2.1 and before 5.3.0 contain an IP spoofing vulnerability in the RealIP middleware, which blindly trusts the first (leftmost) value of the X-Forwarded-For HTTP header. A remote attacker can bypass IP-based access control lists and rate-limiting mechanisms, and forge log entries, by supplying a spoofed IP address in the X-Forwarded-For header. The issue is fixed in version 5.3.0.