CVE-2025-66563Public exploitNetwork attack vector

Stored XSS via unescaped quote fields

Published Dec 4, 2025 · Updated Dec 5, 2025

Stored XSS in Monkeytype 25.49.0 and earlier allows remote attackers to run JavaScript when another user views a malicious quote submission. The quote-approval modal's updateList function interpolates quote.text and quote.source directly into textarea and input markup without HTML escaping. Exploitation requires another user to open the submitted quote, exposing that viewer's session data and permitting actions in the browser context.

CVSS severity7.1
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Monkeytype 25.49.0 and earlier allows remote attackers to run JavaScript when another user views a malicious quote submission. The quote-approval modal's updateList function interpolates quote.text and quote.source directly into textarea and input markup without HTML escaping. Exploitation requires another user to open the submitted quote, exposing that viewer's session data and permitting actions in the browser context.

The record

CVE
CVE-2025-66563
Published
Dec 4, 2025
Updated
Dec 5, 2025
Vendor
Monkeytype
Product
Monkeytype
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 4, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 5, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=<= 25.49.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Monkeytype · Monkeytypeversion=<= 25.49.0

Published CVSS scores

6.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
7.1GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript/JScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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