{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "3.0.0-beta.2"
              },
              {
                "fixed": "3.3.0"
              },
              {
                "introduced": "0"
              },
              {
                "fixed": "2.52.14"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "9ba57651654b640c6859f624543e8ea51726d02b"
            },
            {
              "introduced": "0"
            },
            {
              "fixed": "a39a035dee6df089d94f4f78e34dd34dac895aee"
            },
            {
              "fixed": "a74500f6335abc020023d3581a46ba56a893edc3"
            },
            {
              "fixed": "1403cc8292da3220e9316960b4030cc722a0f396"
            },
            {
              "fixed": "33c9501288ab47a429c8b5e701493f0c3c0af37d"
            }
          ],
          "repo": "https://github.com/gofiber/fiber",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-gcfq-8gqf-4876"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-290"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45045.json"
  },
  "details": "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.",
  "id": "CVE-2026-45045",
  "modified": "2026-07-15T01:48:54.474704255Z",
  "published": "2026-07-08T19:26:26.580Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/gofiber/fiber/releases/tag/v2.52.14"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gofiber/fiber/releases/tag/v3.3.0"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45045.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/gofiber/fiber/security/advisories/GHSA-gcfq-8gqf-4876"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45045"
    },
    {
      "type": "FIX",
      "url": "https://github.com/gofiber/fiber/commit/1403cc8292da3220e9316960b4030cc722a0f396"
    },
    {
      "type": "FIX",
      "url": "https://github.com/gofiber/fiber/commit/33c9501288ab47a429c8b5e701493f0c3c0af37d"
    },
    {
      "type": "FIX",
      "url": "https://github.com/gofiber/fiber/pull/4260"
    },
    {
      "type": "FIX",
      "url": "https://github.com/gofiber/fiber/pull/4495"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Fiber: X-Real-IP Spoofing via Header.Add() in BalancerForward"
}