CVE-2026-45045
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…
Does this matter?
Lower severity and a low EPSS score (0.46%). Track it; it rarely justifies an emergency change on its own.
Description
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.
- CVSS 3.1
- 5.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- EPSS
- 0.46% probability · 39th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-290
- Affected
- gofiber/fiber
- Source
- security-advisories@github.com
References
- https://github.com/gofiber/fiber/commit/1403cc8292da3220e9316960b4030cc722a0f396Patch
- https://github.com/gofiber/fiber/commit/33c9501288ab47a429c8b5e701493f0c3c0af37dPatch
- https://github.com/gofiber/fiber/pull/4260Issue Tracking, Patch
- https://github.com/gofiber/fiber/pull/4495Issue Tracking, Patch
- https://github.com/gofiber/fiber/releases/tag/v2.52.14Release Notes
- https://github.com/gofiber/fiber/releases/tag/v3.3.0Release Notes
- https://github.com/gofiber/fiber/security/advisories/GHSA-gcfq-8gqf-4876Exploit, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.