vciy

CVE-2021-35033

INDEX BUILT · 2026-09-20

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A vulnerability in specific versions of Zyxel NBG6818, NBG7815, WSQ20, WSQ50, WSQ60, and WSR30 firmware with pre-configured password management could…

CVE-2021-350334 of 4 sources documented this
26

rank 26 = 0 + 20 + 0 + 6 + 0

rank@v1 · scheduled

Someone is already using it

CISA KEV catalog · public proof-of-concept · FIRST EPSS

EPSS 0.00409  ·  without this subject the record ranks 26

What it costs you if it fires

NVD CVSS base score, then the CNA's own

CVSS 7.8, from NVD  ·  without this subject the record ranks 6

It is getting worse, not staying still

FIRST EPSS series, rescorings and bad loads removed

no persisting rise in 365 days  ·  without this subject the record ranks 26

How much of the world it touches

NVD CPE configurations

6 products in the CPE ranges  ·  without this subject the record ranks 20

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 26

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$20,400over the next 30 days, if this record is yours
Movementno material movementthe record holds only daily drift and scoring model releases
Basisassumeda published average, not your estate

$20,400 = $4.99M incident cost x 1 exposure x 0.00409 likelihood

udv@v1 · unaudited · wrong for you until you say what you run

$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.

Hindsight · the state

0.00409EPSSNOT IN KEVas of 2026-09-20
Severity7.8 HIGHreceipt
Harmtotal lossreceipt
Exploitationnone in held sources
Defenseunaffected versions publishedreceipt
Movementrisenreceipt
PLATEAU10Minimal movement since 2021-11-24, 1757 days at 0.00, as of 2026-09-16. arc-rules@v1

Foresight · where to check next

No weakness class or product neighbourhood is held for this record, so this index cannot name anywhere to check next. That is an absence in the record, not a finding about the software.

Color is a claim, not decoration:the hostile worldthe defenseno signal

Running Zyxel NBG6818 series firmware? Check your version

A deterministic range check against the ranges this record publishes. It tells you where a version sits in the record, not whether your deployment is exploitable. No account needed.

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AcceptDeferPatch by…Not affectedMitigated

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Harm, if it fires from the vector and the weakness

Written for the ticket you're about to file.

Reachneeds local access · no privileges required · user interaction required · low attack complexityreceipt
ImpactComplete confidentiality, integrity and availability lossreceipt
Scored fromCVSS v3.1 · the CNA's vectorreceipt
Weakness classCWE-260 Password in Configuration Filereceipt
Published consequencesCWE-260: Access Control: Gain Privileges or Assume Identity[email protected]

CISA KEV & Federal Remediation Deadline from the record and CISA

The fix, and how long it's been waiting.

First unaffected version, by branchwsr30 firmware 1.00\(abmy.12\)c0; nbg6818 firmware 1.00\(absc.5\)c0; nbg7815 firmware 1.00\(absk.7\)c0; wsq20 firmware 1.00\(abof.11\)c0; wsq50 firmware 2.20\(abkj.7\)c0…receipt
Patch available sinceNo dated patch-availability record in held sources. The index holds reference URLs without dates and only the current revision of the CVE record, so the day a fix first existed cannot be derived. Only the versions it landed in.

Exploit Status & Known PoCs a ladder, not a score

Current rung: Nothing observed in held sources.

  • RUNG 1Nothing observed in held sources
  • RUNG 2Proof-of-concept published
  • RUNG 3Exploited in the wild · CISA KEV listed
  • RUNG 4Ransomware campaign use known

Authority who says so

CVSS, the CNA7.8 HIGHreceipt
CVSS, NVD7.8 HIGHreceipt
Exploit probability0.00409 · top 65% of all CVEsreceipt
Blast breadth6 products across 1 vendorderived
Assigned byZyxelreceipt
Recorded changes14 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productZyxel NBG6818 series firmware; Zyxel NBG7815 series firmware; Zyxel WSQ20 series firmware; Zyxel WSQ50 series firmware; Zyxel WSQ60 series firmware; Zyxel WSR30 series firmwarereceipt
Published rangeszyxel nbg6818 firmware < 1.00\(absc.5\)c0; zyxel nbg7815 firmware < 1.00\(absk.7\)c0; zyxel wsq20 firmware < 1.00\(abof.11\)c0; zyxel wsq50 firmware < 2.20\(abkj.7\)c0receipt
Show all 6 published ranges
zyxel nbg6818 firmware < 1.00\(absc.5\)c0
zyxel nbg7815 firmware < 1.00\(absk.7\)c0
zyxel wsq20 firmware < 1.00\(abof.11\)c0
zyxel wsq50 firmware < 2.20\(abkj.7\)c0
zyxel wsq60 firmware < 2.20\(abnd.8\)c0
zyxel wsr30 firmware < 1.00\(abmy.12\)c0

A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.

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Attack path

Local accessrequires user interactionZyxel WSQ20 series firmwareCWE-260 weaknessFull compromise (C/I/A)C:H / I:H / A:Hexploits CWE-260data compromise

What it is stated by the CNA

A vulnerability in specific versions of Zyxel NBG6818, NBG7815, WSQ20, WSQ50, WSQ60, and WSR30 firmware with pre-configured password management could allow an attacker to obtain root access of the device, if the local attacker dismantles the device and uses a USB-to-UART cable to connect the device, or if the remote assistance feature had been enabled by an authenticated user. receipt

NVD's analysis a second authority

severity
7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
weakness
CWE-260; CWE-287
affected versions
zyxel nbg6818 firmware < 1.00\(absc.5\)c0; zyxel nbg7815 firmware < 1.00\(absk.7\)c0; zyxel wsq20 firmware < 1.00\(abof.11\)c0; and 3 more, listed in full below
also scored by
[email protected] 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

check it yourself zyxel.com tenable.com receipt

Movement the material steps

24 Nov 20210.00221
7 Mar 20234.2e-4 · scoring model v2023.03.01
17 Mar 20250.00123 · scoring model v2025.03.14
15 Jun 20260.00396 · scoring model v2026.06.15
16 Sep 20260.00409
Show all 14 observations
24 Nov 20210.00221
6 Jan 20220.00985
4 Feb 20220.01404
1 Apr 20220.00885
7 Mar 20234.2e-4
8 Mar 20230.00042
17 Mar 20250.00123
29 Mar 20250.002
30 Mar 20250.00123
7 Apr 20250.00115
10 Apr 20250.00036
17 Mar 20260.00115
15 Jun 20260.00396
16 Sep 20260.00409

14 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt

The full biography

EPSS 0.00409Published2021-11-23Index as of2026-09-16

The record had been public for 4 years, 9 months when this index was last written.

Published 2021-11-23 receipt · Index as of 2026-09-16 derived

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