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

CVSS 5.3 · Medium EPSS 0.36% · P29

Possible ATT&CK Techniques 1AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProductVersion RangeStatus
gofiberfiber>= 3.0.0-beta.2, < 3.3.0affected
< 2.52.14affected
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I. Basic Information for CVE-2026-45045

Vulnerability Information
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Vulnerability Title
Fiber: X-Real-IP Spoofing via Header.Add() in BalancerForward
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用欺骗进行的认证绕过
Source: CVE Program / CVE List V5
Vulnerability Title
Fiber 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Fiber Fiber是Fiber团队的一款开发框架。 Fiber存在授权问题漏洞，该漏洞源于BalancerForward代理辅助程序在注入X-Real-IP时使用Header.Add()而非Header.Set()，导致攻击者可提供首要X-Real-IP值并将其转发给上游服务器，影响日志记录、速率限制和访问控制。以下版本受到影响：3.3.0版本之前和2.52.14版本之前。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
gofiberfiber >= 3.0.0-beta.2, < 3.3.0 -

II. Public POCs for CVE-2026-45045

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III. Intelligence Information for CVE-2026-45045

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Patches & Fixes for CVE-2026-45045 (5)

Vendor Advisories for CVE-2026-45045 (1)

Other References for CVE-2026-45045 (1)

Same Patch Batch · gofiber · 2026-07-08 · 3 CVEs total

CVE-2026-443325.3 MEDIUMFiber: Username Enumeration via Timing Oracle in BasicAuth Default Authorizer
CVE-2026-536244.8 MEDIUMFiber: HSTS header never set in helmet middleware due to incorrect protocol check

IV. Related Vulnerabilities

Same product: fiber
Same vendor: gofiber
Same weakness: CWE-290

V. Comments for CVE-2026-45045

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