# CVE-2020-15111: CRLF vulnerability in Fiber

> Attackers can inject CRLF characters via filenames in Fiber's Attachment method to manipulate headers or redirect users.

- **Severity:** Medium 4.2 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 20 Jul 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-9cx9-x2gp-9qvh, GO-2021-0108

## What is CVE-2020-15111?

CVE-2020-15111 is a medium-severity vulnerability in gofiber fiber, published on 20 Jul 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

In Fiber before version 1.12.6, the filename that is given in c.Attachment() (https://docs.gofiber.io/ctx#attachment) is not escaped, and therefore vulnerable for a CRLF injection attack. I.e. an attacker could upload a custom filename and then give the link to the victim. With this filename, the attacker can change the name of the downloaded file, redirect to another site, change the authorization header, etc. A possible workaround is to serialize the input before passing it to ctx.Attachment().

Weakness: CWE-93 (Improper Neutralization of CRLF Sequences), CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component)

## Which versions are affected by CVE-2020-15111?

3 open source packages ship an affected version, including github.com/gofiber/fiber. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/gofiber/fiber` | Go | All versions | 1.12.6 |
| `github.com/gofiber/fiber` | Go | All versions | 1.12.6 |
| `github.com/gofiber/fiber` | Go | All versions | 1.12.6 |

Products: Gofiber Fiber.

## How do I fix CVE-2020-15111?

Upgrade github.com/gofiber/fiber to 1.12.6 or later.

## Is CVE-2020-15111 being exploited?

There is no known exploitation of CVE-2020-15111 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-2020-15111 and fix it if it is affected.

What it is: CVE-2020-15111 is a medium-severity vulnerability in gofiber fiber, published on 20 Jul 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-15111 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/gofiber/fiber (Go): affected all versions; fixed in 1.12.6
- github.com/gofiber/fiber (Go): affected all versions; fixed in 1.12.6
- github.com/gofiber/fiber (Go): affected all versions; fixed in 1.12.6

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-2020-15111/ (Markdown: https://insights.sbomify.com/CVE-2020-15111/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-15111
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-15111
- OSV: https://osv.dev/vulnerability/CVE-2020-15111

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-15111/
Summaries are generated and may contain mistakes; the official description above is the record.