CVE-2025-6599Network attack vector

Management interface disruption via Slowloris connections

Published Nov 18, 2025 · Updated Nov 18, 2025

Uncontrolled resource consumption in Zyxel DX3301-T0 firmware 5.50(ABVY.6.3)C0 and earlier allows remote attackers to block HTTP requests. The device web server does not adequately limit resources held by Slowloris-style connections, allowing incomplete requests to occupy HTTP handling capacity; Zyxel has not disclosed the affected function or resource limit. Network access to web management is sufficient, and exploitation temporarily disrupts only management-interface availability while other networking services continue.

CVSS severity5.3
Medium
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in Zyxel DX3301-T0 firmware 5.50(ABVY.6.3)C0 and earlier allows remote attackers to block HTTP requests. The device web server does not adequately limit resources held by Slowloris-style connections, allowing incomplete requests to occupy HTTP handling capacity; Zyxel has not disclosed the affected function or resource limit. Network access to web management is sufficient, and exploitation temporarily disrupts only management-interface availability while other networking services continue.

The record

CVE
CVE-2025-6599
Published
Nov 18, 2025
Updated
Nov 18, 2025
Vendor
Zyxel Networks
Product
DX3301-T0 Firmware
Classifications
CWE-400, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 18, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 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=<= 5.50(ABVY.6.3)C0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zyxel Networks · DX3301-T0 Firmwareversion=<= 5.50(ABVY.6.3)C0

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.3Zyxel CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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-400Uncontrolled Resource Consumption
T1499.003Application Exhaustion Flood

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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