CVE-2020-15111: Github.com/gofiber/fiber CRLF Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-9cx9-x2gp-9qvh
CVSS 4.2
CWE-74 CWE-93
Published
Advisory Summary

CVE-2020-15111 is a MODERATE (CVSS 4.2) crlf vulnerability vulnerability (CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')) affecting Github.com/gofiber/fiber libraries in the Go ecosystem. The issue involves crlf vulnerability in fiber. Remediation is available by upgrading affected packages to version 1.12.6.

CVE-2020-15111 at a Glance

CVE Identifier CVE-2020-15111
GHSA Identifier GHSA-9cx9-x2gp-9qvh
Severity MODERATE
CVSS v3.1 Base Score 4.2
CWE Classification CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Affected Product Github.com/gofiber/fiber
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 4.2

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2020-15111

To remediate this vulnerability, upgrade all affected Github.com/gofiber/fiber dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/gofiber/fiber fixed: 1.12.6
Upgrade github.com/gofiber/fiber to 1.12.6
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

inspect dependencies for github.com/gofiber/fiber

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-15111, inspect your project dependencies for Github.com/gofiber/fiber:

inspect dependencies for github.com/gofiber/fiber

Analyze the terminal output to locate any version of Github.com/gofiber/fiber in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.12.6), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection'), where the product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. In Github.com/gofiber/fiber, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact 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. ### Steps to reproduce ```go package main import "github.com/gofiber/fiber" const badFileName = "another secret document.pdf\"\r\nLocation: google.com\r\nAuthorization: \"example_of_session_fixation" func splitTheResponse(c *fiber.Ctx) { c.Attachment(badFileName) } func main() { app := fiber.New() app.Get("/attack", splitTheResponse) app.Listen("127.0.0.1:8080") } ``` ``` HTTP/1.1 200 OK Date: Fri, 10 Jul 2020 19:47:04 GMT Content-Type: application/octet-stream Content-Length: 0 Content-Disposition: attachment; filename="another secret document.pdf" Location: google.com Authorization: "example_of_session_fixation" ``` ### Patches This issue has been patched in `v1.12.6` with commit [579](https://github.com/gofiber/fiber/pull/579/commits/f698b5d5066cfe594102ae252cd58a1fe57cf56f) escaping the filename by default. ### Workarounds You could of course serialize the input yourself before passing it to `ctx.Attachment()`, this is actually a good practice by default. But in case you forget, we got you covered 👍 ### References A CRLF injection attack is one of several types of injection attacks. It can be used to escalate to more malicious attacks such as Cross-site Scripting (XSS), page injection, web cache poisoning, cache-based defacement, and more. A CRLF injection vulnerability exists if an attacker can inject the CRLF characters into a web application, for example using a user input form or an HTTP request, [see acunetix](https://www.acunetix.com/websitesecurity/crlf-injection/) ### For more information If you have any questions or comments about this advisory: * Open an issue in [gofiber/fiber](https://github.com/gofiber/fiber) * Join us on [Discord](https://gofiber.io/discord)

CVE-2020-15111 Affected Github.com/gofiber/fiber Versions

1 component(s)
Fixed Versions:
1.12.6
Product / Package Ecosystem Affected Versions Fixed Version
github.com/gofiber/fiber
Go
< 1.12.6
1.12.6

References

Frequently Asked Questions

What is CVE-2020-15111?
CVE-2020-15111 is a security vulnerability in Github.com/gofiber/fiber involving CRLF vulnerability in Fiber under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection').
Which Github.com/gofiber/fiber versions are affected?
Affected versions include releases prior to 1.12.6 across affected packages: github.com/gofiber/fiber.
What version fixes CVE-2020-15111?
Upgrading to 1.12.6 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/gofiber/fiber affected?
Yes, github.com/gofiber/fiber is affected in releases prior to 1.12.6. Upgrade your dependency to 1.12.6 or later.
What is the CVSS score of CVE-2020-15111?
CVE-2020-15111 has a CVSS v3.1 base score of 4.2 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2020-15111?
CVE-2020-15111 is classified under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') (The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.).
How can I check Go dependencies for CVE-2020-15111?
Run the dependency tree command: 'inspect dependencies for github.com/gofiber/fiber'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-9cx9-x2gp-9qvh",
  "modified" : "2023-02-09T17:46:27Z",
  "published" : "2021-06-29T21:24:28Z",
  "aliases" : [ "CVE-2020-15111" ],
  "summary" : "CRLF vulnerability in Fiber",
  "details" : "### Impact\nThe 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.\n\n### Steps to reproduce\n```go\npackage main\n\nimport \"github.com/gofiber/fiber\"\n\nconst badFileName = \"another secret document.pdf\\\"\\r\\nLocation: google.com\\r\\nAuthorization: \\\"example_of_session_fixation\"\n\nfunc splitTheResponse(c *fiber.Ctx) {\n\tc.Attachment(badFileName)\n}\n\nfunc main() {\n\tapp := fiber.New()\n\tapp.Get(\"/attack\", splitTheResponse)\n\tapp.Listen(\"127.0.0.1:8080\")\n}\n```\n```\nHTTP/1.1 200 OK\nDate: Fri, 10 Jul 2020 19:47:04 GMT\nContent-Type: application/octet-stream\nContent-Length: 0\nContent-Disposition: attachment; filename=\"another secret document.pdf\"\nLocation: google.com\nAuthorization: \"example_of_session_fixation\"\n```\n\n### Patches\nThis issue has been patched in `v1.12.6` with commit [579](https://github.com/gofiber/fiber/pull/579/commits/f698b5d5066cfe594102ae252cd58a1fe57cf56f) escaping the filename by default.\n\n### Workarounds\nYou could of course serialize the input yourself before passing it to `ctx.Attachment()`, this is actually a good practice by default. But in case you forget, we got you covered 👍 \n\n### References\nA CRLF injection attack is one of several types of injection attacks. It can be used to escalate to more malicious attacks such as Cross-site Scripting (XSS), page injection, web cache poisoning, cache-based defacement, and more. A CRLF injection vulnerability exists if an attacker can inject the CRLF characters into a web application, for example using a user input form or an HTTP request, [see acunetix](https://www.acunetix.com/websitesecurity/crlf-injection/)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [gofiber/fiber](https://github.com/gofiber/fiber)\n* Join us on [Discord](https://gofiber.io/discord)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/gofiber/fiber"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.12.6"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/gofiber/fiber/security/advisories/GHSA-9cx9-x2gp-9qvh"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-15111"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gofiber/fiber/pull/579"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gofiber/fiber/commit/f698b5d5066cfe594102ae252cd58a1fe57cf56f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/gofiber/fiber"
  }, {
    "type" : "WEB",
    "url" : "https://pkg.go.dev/vuln/GO-2021-0108"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-74", "CWE-93" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-24T19:14:18Z",
    "nvd_published_at" : "2020-07-20T18:15:00Z"
  }
}