Home/CVE/Nu Html Checker (validator.nu) contains a restriction bypass that allows remote attackers to make the server perform arb
CVE

CVE-2025-15104

Nu Html Checker (validator.nu) contains a restriction bypass that allows remote attackers to make the server perform arb

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).

MEDIUM · CVSS 5.3 EPSS 0.00029
Schedule remediation
  • Public exploit or PoC is available
  • SSVC automatable: yes - attacks can be scripted at scale
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-918Server-Side Request Forgery (SSRF)
▤

Affected Products & Versions

1
validator< 2026-01-11
▤

Affected Packages

2
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Maven nu.validator:validator MODERATE
npm vnu-jar MODERATE
⚠

Public Exploits & PoCs

1
pocfluidattacks.com · europefluidattacks.com
▣

Scoring & Timeline

5.3
MEDIUM · CVSS v3.1 · help@fluidattacks.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD16 Jan 2026 · 02:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
SSVC triage · cisa-vulnrichment
Exploitation
poc
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/validator/validatorProduct
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