CVE-2026-45045 PUBLISHED

Fiber is an Express inspired web framework written in Go. Prior to 3.3.0 and 2.52.14, the BalancerForward proxy helper in middleware/proxy/proxy.go uses Header.Add() instead of Header.Set() when injecting X-Real-IP, allowing an attacker-supplied first X-Real-IP value to be forwarded to upstream servers for logging, rate limiting, and access control. This issue is fixed in version 3.3.0 and 2.52.14.

• https://github.com/gofiber/fiber/security/advisories/GHSA-gcfq-8gqf-4876
• https://github.com/gofiber/fiber/pull/4260
• https://github.com/gofiber/fiber/pull/4495
• https://github.com/gofiber/fiber/commit/1403cc8292da3220e9316960b4030cc722a0f396
• https://github.com/gofiber/fiber/commit/33c9501288ab47a429c8b5e701493f0c3c0af37d
• https://github.com/gofiber/fiber/releases/tag/v2.52.14
• https://github.com/gofiber/fiber/releases/tag/v3.3.0

• CWE-290: Authentication Bypass by Spoofing CWE