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

> Attackers can spoof X-Real-IP headers in Fiber proxy middleware, bypassing upstream rate limiting and access controls.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Jul 2026
- **Updated:** 9 Jul 2026
- **Also known as:** GHSA-gcfq-8gqf-4876, GO-2026-5887, MINI-5g7v-9g4p-6349, MINI-6r5m-9fvh-3mx8, MINI-7w8h-jr24-h956, MINI-8vvp-fqcg-3cqh, UBUNTU-CVE-2026-45045

## What is CVE-2026-45045?

CVE-2026-45045 is a medium-severity vulnerability in gofiber fiber, published on 8 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-290 (Authentication Bypass by Spoofing)

## Which versions are affected by CVE-2026-45045?

5 open source packages ship an affected version, including github.com/gofiber/fiber/v3 and github.com/gofiber/fiber/v2. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/gofiber/fiber/v3` | Go | All versions | 3.3.0 |
| `github.com/gofiber/fiber/v3` | Go | All versions | 3.3.0 |
| `github.com/gofiber/fiber/v3` | Go | All versions | 3.3.0 |
| `github.com/gofiber/fiber/v2` | Go | All versions | 2.52.14 |
| `github.com/gofiber/fiber/v2` | Go | All versions | 2.52.14 |

Products: Gofiber Fiber.

## How do I fix CVE-2026-45045?

Upgrade github.com/gofiber/fiber/v3 to 3.3.0 or later.

## Is CVE-2026-45045 being exploited?

There is no known exploitation of CVE-2026-45045 in the wild and no public exploit code.

## Other vulnerabilities in gofiber fiber

- [CVE-2024-38513](https://insights.sbomify.com/CVE-2024-38513/): Fiber Session Middleware Token Injection Vulnerability (critical 10.0)
- [CVE-2023-45128](https://insights.sbomify.com/CVE-2023-45128/): CSRF Token Reuse Vulnerability in fiber (critical 10.0)
- [CVE-2024-25124](https://insights.sbomify.com/CVE-2024-25124/): Fiber has Insecure CORS Configuration, Allowing Wildcard Origin with Credentials (critical 9.4)
- [CVE-2025-66630](https://insights.sbomify.com/CVE-2025-66630/): Fiber insecurely fallsback in utils.UUIDv4() / utils.UUID() — predictable / zero‑UUID on crypto/rand failure (critical 9.2)
- [CVE-2025-54801](https://insights.sbomify.com/CVE-2025-54801/): Fiber Susceptible to Crash via `BodyParser` Due to Unvalidated Large Slice Index in Decoder (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45045 and fix it if it is affected.

What it is: CVE-2026-45045 is a medium-severity vulnerability in gofiber fiber, published on 8 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-45045 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/gofiber/fiber/v3 (Go): affected all versions; fixed in 3.3.0
- github.com/gofiber/fiber/v3 (Go): affected all versions; fixed in 3.3.0
- github.com/gofiber/fiber/v3 (Go): affected all versions; fixed in 3.3.0
- github.com/gofiber/fiber/v2 (Go): affected all versions; fixed in 2.52.14
- github.com/gofiber/fiber/v2 (Go): affected all versions; fixed in 2.52.14

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-45045/ (Markdown: https://insights.sbomify.com/CVE-2026-45045/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45045
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45045
- OSV: https://osv.dev/vulnerability/CVE-2026-45045

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45045/
Summaries are generated and may contain mistakes; the official description above is the record.