CVE-2025-15104Disclosure(validator / validator)

LOWCVSS 5.3 · MEDIUM

Signal is active with 1 mentions in latest observed window

Immediate actions

Track advisory updates for patch or workaround availability

Recommended action window: Monitor and triage in normal cycle

NVD 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).

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0.0/ 10 priority

Sources & remediation

Exploit / PoC references

Other references

https://github.com/validator/validator

Weakness type (CWE)

CWE-918

Priority

LOW

Exploitation

NONE

PoC

YES

Patch

NONE

Momentum

NONE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

validator

Threat summary

1 mentions across 1 observed day

What's happening

Disclosure: 1 classified signal
1 total mentions across 1 day

Affected systems

Vendors

validator

Products

validator

Deep dive

Activity timeline1 mentions / 1d

Signal classification1 categories

Disclosure

1100.0%

Referenced assets2 URLs

By indicator

Full discourse1 post

Fluid Attacks@fluidattacks206d
Disclosure
Fluid Attacks' research team found a zero-day vulnerability in The Nu Html Checker (vnu). As a #CNA, we assigned the ID CVE-2025-15104. Details here: 🔗https://fluidattacks.com/advisories/europe. We have disclosed 224 #CVE to this date: 🔗https://fluidattacks.com/advisories/. https://t.co/9gdaFqkOFg
Post summary
Fluid Attacks announces a new zero‑day vulnerability CVE-2025-15104 in the Nu Html Checker, providing an advisory link but no exploit details or patch information.
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CPE platform detail1 entries

Part:

Vendor:

Product:

Version:

Target SW:

Target HW:

1 of 1 entries

Part	Vendor	Product	Version	Target SW	Target HW
App	validator	validator	-	-	-

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