Vulnerability in Gofiber Fiber
CVE-2026-45045
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.005 (38.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 38.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Gofiber Fiber — versions >= 3.0.0-beta.2, < 3.3.0, < 2.52.14
Weakness classification (CWE)
References
- github.com/gofiber/fiber/security/advisories/GHSA-gcfq-8gqf-4876 (Exploit, Vendor Advisory)
- github.com/gofiber/fiber/pull/4260 (Patch, Issue Tracking)
- github.com/gofiber/fiber/pull/4495 (Patch, Issue Tracking)
- github.com/gofiber/fiber/commit/1403cc8292da3220e9316960b4030cc722a0f396 (Patch)
- github.com/gofiber/fiber/commit/33c9501288ab47a429c8b5e701493f0c3c0af37d (Patch)
- github.com/gofiber/fiber/releases/tag/v2.52.14 (Release Notes)
- github.com/gofiber/fiber/releases/tag/v3.3.0 (Release Notes)
Frequently asked questions
- What is CVE-2026-45045?
- CVE-2026-45045 is a medium-severity vulnerability in Gofiber Fiber, classified under Authentication Bypass by Spoofing. CVSS score: 5.3/10. Published 2026-07-08.
- How severe is CVE-2026-45045?
- Medium severity. CVSS v3 base score is 5.3 out of 10.