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

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Summary

CVECVE-2026-45045
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-08 20:16:50 UTC
Updated2026-07-10 19:01:16 UTC
DescriptionFiber 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.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS: 0.004550000 probability, percentile 0.365360000 (date 2026-07-12)

Problem Types: CWE-290 | CWE-290 CWE-290: Authentication Bypass by Spoofing

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Gofiber Fiber affected >= 3.0.0-beta.2, < 3.3.0 Not specified
CNA Gofiber Fiber affected < 2.52.14 Not specified

References

ReferenceSourceLinkTags
github.com/gofiber/fiber/releases/tag/v3.3.0 [email protected] github.com
github.com/gofiber/fiber/commit/33c9501288ab47a429c8b5e701493f0c3c0af37d [email protected] github.com
github.com/gofiber/fiber/pull/4495 [email protected] github.com
github.com/gofiber/fiber/security/advisories/GHSA-gcfq-8gqf-4876 [email protected] github.com
github.com/gofiber/fiber/pull/4260 [email protected] github.com
github.com/gofiber/fiber/releases/tag/v2.52.14 [email protected] github.com
github.com/gofiber/fiber/commit/1403cc8292da3220e9316960b4030cc722a0f396 [email protected] github.com
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