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CVE-2021-35033

25
FAUCET Score

CVE-2021-35033 is a high-severity vulnerability affecting specific Zyxel NBG and WSQ series firmware versions, stemming from pre-configured password management. An attacker could gain root access to the device either by physically dismantling it and using a USB-to-UART cable, or remotely if the authenticated user has enabled the remote assistance feature. With a CVSS score of 7.8, the vulnerability has a low attack complexity and requires local or authenticated user access, but grants full confidentiality, integrity, and availability impact. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.00\(absc.5\)c0CPE matchmatch criteria
cpe:2.3:o:zyxel:nbg6818_firmware:*:*:*:*:*:*:*:*
< 1.00\(absk.7\)c0CPE matchmatch criteria
cpe:2.3:o:zyxel:nbg7815_firmware:*:*:*:*:*:*:*:*
< 1.00\(abof.11\)c0CPE matchmatch criteria
cpe:2.3:o:zyxel:wsq20_firmware:*:*:*:*:*:*:*:*
< 2.20\(abkj.7\)c0CPE matchmatch criteria
cpe:2.3:o:zyxel:wsq50_firmware:*:*:*:*:*:*:*:*
< 2.20\(abnd.8\)c0CPE matchmatch criteria
cpe:2.3:o:zyxel:wsq60_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.8HIGH

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.40%
Probability of exploitation in next 30 days
EPSS Percentile
32.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0040 is in the 72nd percentile among its peer group of 17,061 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (3)

giteavendor investigatingvia llm_extracted
meterspherevendor investigatingvia llm_extracted
qnapvendor investigatingvia llm_extracted

Vendor Advisories (3)

giteallm-gitea-f1eb80b491ad297dHIGH

Zyxel Routers and Home WiFi Systems - Unprotected Root Access via UART Using Default Password

Feb 28, 2022
qnapllm-qnap-abe132ec8d3695caHIGH

Zyxel Routers and Home WiFi Systems - Unprotected Root Access via UART Using Default Password

Feb 28, 2022
meterspherellm-metersphere-669c8c8c61d9bae0HIGH

Zyxel Routers and Home WiFi Systems - Unprotected Root Access via UART Using Default Password

Feb 28, 2022

References

tenable.com / security/research/tra-2022-06
ExploitThird Party Advisory
zyxel.com / support/Zyxel_security_advisory_for_pre-configured_password_management_vulnerability_of_home_routers_and_WiFi_systems.shtml
Vendor Advisory