CVE-2025-15104

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).

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://fluidattacks.com/advisories/europe	Exploit Third Party Advisory
https://github.com/validator/validator	Product
https://fluidattacks.com/advisories/europe	Exploit Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:validator:validator:*:*:*:*:*:*:*:*

History

23 Jan 2026, 16:57

Type	Values Removed	Values Added
First Time		Validator Validator validator
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 5.3
CPE		cpe:2.3:a:validator:validator::::::::
References	~~() https://fluidattacks.com/advisories/europe -~~	() https://fluidattacks.com/advisories/europe - Exploit, Third Party Advisory
References	~~() https://github.com/validator/validator -~~	() https://github.com/validator/validator - Product

16 Jan 2026, 15:15

Type	Values Removed	Values Added
References	~~() https://fluidattacks.com/advisories/europe -~~	() https://fluidattacks.com/advisories/europe -

16 Jan 2026, 14:15

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-01-16 14:15

Updated : 2026-01-23 16:57

NVD link : CVE-2025-15104

Mitre link : CVE-2025-15104

CVE.ORG link : CVE-2025-15104

JSON object : View

Products Affected

validator

validator

CWE

CWE-918

Server-Side Request Forgery (SSRF)

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