Medium 5.3Published Jul 8, 2026

CVE-2026-45045Fiber: X-Real-IP Spoofing via Header.Add() in BalancerForward

Updated under an hour ago (Oct 27, 2026, 7:23 AM ET)

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It affects gofiber fiber. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for gofiber fiber

Exploited in the last 30 days

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: 5.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness (CWE): CWE-290
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Jul 9, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

gofiber fiber gofiber:fiber (from the name)	from 3.0.0-beta.2, < 3.3.0; before 2.52.14	CNA record
gofiber fiber gofiber:fiber	before 2.52.14; from 3.0.0 before 3.3.0	NVD

References

References

https://github.com/gofiber/fiber/security/advisories/GHSA-gcfq-8gqf-4876	x-refsource-confirm, exploit, vendor-advisory
https://github.com/gofiber/fiber/pull/4260	x-refsource-misc, issue-tracking, patch
https://github.com/gofiber/fiber/pull/4495	x-refsource-misc, issue-tracking, patch
https://github.com/gofiber/fiber/commit/1403cc8292da3220e9316960b4030cc722a0f396	x-refsource-misc, patch
https://github.com/gofiber/fiber/commit/33c9501288ab47a429c8b5e701493f0c3c0af37d	x-refsource-misc, patch
https://github.com/gofiber/fiber/releases/tag/v2.52.14	x-refsource-misc, release-notes
https://github.com/gofiber/fiber/releases/tag/v3.3.0	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.