CVE-2025-66563

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).

CVSS v3.1 Score

6.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

Affected Products

Vendor	Product	Versions
monkeytype	monkeytype	< 25.49.0

References

Advisories & Patches

https://github.com/monkeytypegame/monkeytype/commit/d6d062a77132ba7d6ba3b482d46ae329d3b8d695 https://github.com/monkeytypegame/monkeytype/security/advisories/GHSA-mfjh-9552-8g27 https://github.com/monkeytypegame/monkeytype/security/advisories/GHSA-mfjh-9552-8g27

Exploits

https://github.com/monkeytypegame/monkeytype/security/advisories/GHSA-mfjh-9552-8g27 https://github.com/monkeytypegame/monkeytype/security/advisories/GHSA-mfjh-9552-8g27

Frequently Asked Questions

What is CVE-2025-66563? +

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). It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2025-66563? +

CVE-2025-66563 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-66563? +

CVE-2025-66563 affects products from monkeytype, specifically: monkeytype. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-66563? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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