🛡️ CVE-2025-66563 — monkeytype

🟡 CVSS 6.1 — Medium ⚠️ Exploit Public CWE-79 NVD
6.1
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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).

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality low, integrity low, availability none.

Weakness class

CVE-2025-66563 is classified as CWE-79: Cross-site Scripting (XSS). User-supplied data is written into a page without escaping, so attacker script runs in the browser of anyone who views it.

Affected software

CVE-2025-66563 is recorded against 1 package.

  • monkeytype (fixed in 25.49.0)

Timeline and source

Published on 4 December 2025 and last revised on 17 June 2026. A public exploit is known to exist, which raises the urgency of patching considerably. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com
github.com
github.com

Details

Severity MEDIUM
CVSS Score 6.1
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CWE CWE-79
Public Exploit ⚠️ Yes
Source NVD
Published 2025-12-04
Updated 2026-08-11
Modified 2026-06-17

Affected Packages

Software From version Fixed in
monkeytype — 25.49.0

Similar Threats

Exploit Protection

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CVE-2025-66563 carries CVSS 6.1 Medium rating and a public exploit already exists. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

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