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Nbg6818 FirmwareOperating system · Zyxel

CVE-2021-35033

HIGH · 7.8 CVSS v3.1 Published 2021-11-23
Fix available
A fix is available. Upgrade to 1.00 / 2.20 or later.
See remediation →
80/100
Remediation priority · High
Public exploit Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Nbg6818 FirmwareOperating system
Affected:< 1.00\(absc.5\)c0
Nbg7815 FirmwareOperating system
Affected:< 1.00\(absk.7\)c0
Wsq20 FirmwareOperating system
Affected:< 1.00\(abof.11\)c0
Wsq50 FirmwareOperating system
Affected:< 2.20\(abkj.7\)c0
Wsq60 FirmwareOperating system
Affected:< 2.20\(abnd.8\)c0
Wsr30 FirmwareOperating system
Affected:< 1.00\(abmy.12\)c0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.00 / 2.20 or later
Fixed in 1.002.20
Recommended fix High confidence

Device-specific firmware: NBG6818 to 1.00(absc.5)c0 or later; NBG7815 to 1.00(absk.7)c0 or later; WSQ20 to 1.00(abof.11)c0 or later; WSQ50 to 2.20(abkj.7)c0 or later; WSQ60 to 2.20(abnd.8)c0 or later; WSR30 to 1.00(abmy.12)c0 or later

  1. 1. Identify the specific Zyxel device model from the affected list: NBG6818, NBG7815, WSQ20, WSQ50, WSQ60, or WSR30
  2. 2. Download the firmware update from the official Zyxel support website (www.zyxel.com) for your specific model
  3. 3. Ensure the fixed firmware version meets or exceeds: NBG6818 (1.00absc.5c0), NBG7815 (1.00absk.7c0), WSQ20 (1.00abof.11c0), WSQ50 (2.20abkj.7c0), WSQ60 (2.20abnd.8c0), WSR30 (1.00abmy.12c0)
  4. 4. Access the device web management interface or use the firmware upgrade feature
  5. 5. Upload and apply the firmware update
  6. 6. After upgrade, verify the firmware version has been updated successfully
  7. 7. As a secondary precaution, ensure remote assistance feature remains disabled unless explicitly required
Caveat Upgrading firmware may reset device configuration to defaults; backup configuration before upgrade and reapply after

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-35033 in production — separate from our analysis above.

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