CVE-2025-66563
MediumCVSS 6.1Exploitation Probability (EPSS)
Low risk14th percentile - higher than 14% of all known CVEs
Summary
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).
Risk Assessment
An attacker can execute arbitrary JavaScript in the browser of anyone viewing malicious quotes, potentially leading to session or data theft. The risk affects all Monkeytype users.
Recommendation
Update Monkeytype to a version later than 25.49.0 that contains the fix. Until then, consider restricting quote submissions or adding additional input validation.
Other vulnerabilities in Monkeytype
See all- CVE-2026-69183High
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.
- 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 25.49.0 and earlier, there is improper handling of user input which allows an attacker to execute malicious javascript on anyone viewing a malicious quote submission. quote.text and quote.source are user input, and they're inserted straight into the DOM. If they contain HTML tags, they will be rendered (after some escaping using quotes and textarea tags).
Vulnerability data from NVD (NIST) · CISA KEV · EPSS