Description

Nu Html Checker (validator.nu) contains a restriction bypass that allows remote attackers to make the server perform arbitrary HTTP/HTTPS requests to internal resources, including localhost services. While the validator implements hostname-based protections to block direct access to localhost and 127.0.0.1, these controls can be bypassed using DNS rebinding techniques or domains that resolve to loopback addresses.This issue affects The Nu Html Checker (vnu): latest (commit 23f090a11bab8d0d4e698f1ffc197a4fe226a9cd).

INFO

Published Date :

2026-01-16T14:00:16.643Z

Last Modified :

2026-01-16T14:30:55.715Z

Source :

Fluid Attacks
AFFECTED PRODUCTS

The following products are affected by CVE-2025-15104 vulnerability.

Vendors Products
The Nu Html Checker
  • The Nu Html Checker
Validator
  • Validator
REFERENCES

Here, you will find a curated list of external links that provide in-depth information to CVE-2025-15104.

URL Resource
https://fluidattacks.com/advisories/europe cve-icon cve-icon cve-icon
https://github.com/validator/validator cve-icon cve-icon
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CVSS Vulnerability Scoring System

Detailed values of each vector for above chart.
Attack Vector
Attack Complexity
Attack Requirements
Privileges Required
User Interaction
VS Confidentiality
VS Integrity
VS Availability
SS Confidentiality
SS Integrity
SS Availability
Detailed values of each vector for above chart.
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact