CVE-2026-69183
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk40th percentile - higher than 40% of all known CVEs
Summary
Monkeytype 26.26.0 and earlier has a vulnerability in the rate-limit key generator that uses client-controlled cf-connecting-ip and x-forwarded-for headers before req.ip. An unauthenticated attacker can rotate these headers to bypass rate limits, allowing repeated requests to endpoints like forgotPasswordEmail and verificationEmail, causing mail bombing, exhausting Firebase/SMTP quotas, and evading brute-force protection.
Risk Assessment
An attacker could spam users with emails, exhaust external service quotas, and cause resource exhaustion.
Recommendation
Update Monkeytype to a patched version if available. Configure a trusted proxy to overwrite cf-connecting-ip and x-forwarded-for headers.
Other vulnerabilities in Monkeytype
See all- CVE-2025-66563Medium
Monkeytype in version 25.49.0 and earlier improperly handles user input, allowing an attacker to execute malicious JavaScript on anyone viewing a malicious quote submission. quote.text and quote.source are user input and are inserted straight into the DOM; if they contain HTML tags, they will be rendered (after some escaping using quotes and textarea tags).
- CVE-2025-59838Medium
Monkeytype, a typing test application, has an XSS vulnerability due to improper handling of user input when loading a saved custom text. Affects versions 25.36.0 and prior; fixed in version 25.44.0.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS