Vulnerabilities in pkg:golang/github.com/gofiber/fiber/v3

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-gcfq-8gqf-4876",
  "modified" : "2026-08-04T21:52:02Z",
  "published" : "2026-07-02T13:50:45Z",
  "aliases" : [ "CVE-2026-45045" ],
  "summary" : "GoFiber Vulnerable to X-Real-IP Spoofing via Header.Add() in BalancerForward",
  "details" : "## Summary\n\nThe `BalancerForward` proxy helper in GoFiber uses `Header.Add()` instead of `Header.Set()` when injecting the `X-Real-IP` header. This appends the real client IP as a second header value rather than replacing any attacker-supplied value. Upstream servers that read the first `X-Real-IP` header (nginx, Express, most HTTP servers) use the attacker's spoofed IP for logging, rate limiting, and access control.\n\n## Vulnerable Code\n\n**File:** `middleware/proxy/proxy.go`, lines 270-285\n\n```go\nfunc BalancerForward(servers []string, clients ...*fasthttp.Client) fiber.Handler {\n    r := &roundrobin{\n        current: 0,\n        pool:    servers,\n    }\n    return func(c fiber.Ctx) error {\n        server := r.get()\n        if !strings.HasPrefix(server, \"http\") {\n            server = \"http://\" + server\n        }\n        c.Request().Header.Add(\"X-Real-IP\", c.IP())   // line 282: Add, not Set\n        return Do(c, server+c.OriginalURL(), clients...)\n    }\n}\n```\n\n## Data Flow\n\n1. Attacker sends request with `X-Real-IP: 10.0.0.1` (spoofed internal IP)\n2. `BalancerForward` handler executes at line 282\n3. `c.Request().Header.Add(\"X-Real-IP\", c.IP())` APPENDS the real IP as a second header\n4. Upstream server receives: `X-Real-IP: 10.0.0.1` AND `X-Real-IP: <real-attacker-ip>`\n5. Most HTTP servers (nginx, Node.js, Apache) read the FIRST value\n6. Upstream uses `10.0.0.1` for all IP-dependent logic\n\n## Impact\n\n- **Rate limit bypass:** IP-based rate limiting at the upstream uses the spoofed IP, allowing unlimited requests\n- **IP ACL bypass:** Internal IP allowlists (e.g., admin panels restricted to `10.0.0.0/8`) can be bypassed\n- **Audit log poisoning:** Security logs record the spoofed IP, making incident investigation unreliable\n- **Geolocation bypass:** IP-based geofencing or region restrictions are circumvented\n\n## Fix\n\nReplace `Header.Add()` with `Header.Set()` at line 282:\n\n```go\nc.Request().Header.Set(\"X-Real-IP\", c.IP())\n```\n\n`Header.Set()` replaces any existing header value, ensuring only the real client IP is forwarded.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/gofiber/fiber/v3"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.3.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 3.2.0"
    }
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/gofiber/fiber/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.52.14"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.52.13"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "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" : "WEB",
    "url" : "https://github.com/gofiber/fiber/pull/4260"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gofiber/fiber/pull/4495"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gofiber/fiber/commit/1403cc8292da3220e9316960b4030cc722a0f396"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gofiber/fiber/commit/33c9501288ab47a429c8b5e701493f0c3c0af37d"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/gofiber/fiber"
  }, {
    "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-290" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-02T13:50:45Z",
    "nvd_published_at" : "2026-07-08T20:16:50Z"
  }
}