CVE-2025-53904Network attack vector

Browser script execution via incomplete denylist

Published Jul 16, 2025 · Updated Jul 18, 2025

Reflected XSS in The Scratch Channel tsc-web-client allows remote attackers to execute script in a user's browser via crafted input. The api/admin.js handler applies an incomplete denylist to request-controlled content before reflecting it into a generated page. Exploitation requires a user to open the resulting content, and execution remains within that browser's security context.

CVSS severity4.0
Medium
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in The Scratch Channel tsc-web-client allows remote attackers to execute script in a user's browser via crafted input. The api/admin.js handler applies an incomplete denylist to request-controlled content before reflecting it into a generated page. Exploitation requires a user to open the resulting content, and execution remains within that browser's security context.

The record

CVE
CVE-2025-53904
Published
Jul 16, 2025
Updated
Jul 18, 2025
Vendor
The Scratch Channel
Product
tsc-web-client
Classifications
CWE-692, CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 18, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=<= b66a1cae45e05ad8971aecd96c3322520f8a5725

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Scratch Channel · tsc-web-clientversion=<= b66a1cae45e05ad8971aecd96c3322520f8a5725

Published CVSS scores

4.0GitHubCVSS:3.1/AV:P/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H
1.3GitHub CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-692Incomplete Denylist to Cross-Site Scripting
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

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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