---
id: CVE-2026-69183
title: Monkeytype is a minimalistic and customizable typing test
summary: >-
  Monkeytype is a minimalistic and customizable typing test. In 26.26.0 and
  earlier, the backend rate-limit key generator in
  backend/src/middlewares/rate-limit.ts uses client-controlled cf-connecting-ip
  and x-forwarded-for headers before t…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-290
  - CWE-307
  - CWE-644
published: '2026-08-20'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T20:09:01.757'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-69183'
references:
  - url: >-
      https://github.com/monkeytypegame/monkeytype/security/advisories/GHSA-c878-p3jh-mmjf
    label: security-advisories@github.com
  - url: >-
      https://github.com/monkeytypegame/monkeytype/security/advisories/GHSA-c878-p3jh-mmjf
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.0033
epssPercentile: 0.26362
ingestedAt: '2026-09-18T20:51:25.642Z'
---

## Overview

Monkeytype is a minimalistic and customizable typing test. In 26.26.0 and earlier, the backend rate-limit key generator in backend/src/middlewares/rate-limit.ts uses client-controlled cf-connecting-ip and x-forwarded-for headers before the trust-proxy-derived req.ip value. An unauthenticated attacker can rotate either header to create a new bucket for each request, bypassing rootRateLimiter, badAuthRateLimiter, getKey(), and the getKeyWithUid() fallback used by public endpoints. This permits repeated POST /users/forgotPasswordEmail and verificationEmail requests, mail bombing registered users, consuming Firebase or SMTP quota, evading brute-force protection, and enabling resource exhaustion. Exploitability of cf-connecting-ip depends on deployment topology, but x-forwarded-for and direct-to-origin paths remain affected when those values are not overwritten by a trusted proxy. No fixed version is available as of this review.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.