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CVE-2021-4030

27
FAUCET Score

CVE-2021-4030 is a critical Cross-Site Request Forgery (CSRF) vulnerability affecting Zyxel ARMOR Z1/Z2 firmware, specifically models NBG6816 and NBG6817. This flaw allows an attacker to execute arbitrary commands on the device if a local user is tricked into visiting a malicious website. With a CVSS score of 8.8 (HIGH), the vulnerability has a low attack complexity and high impact on confidentiality, integrity, and availability, requiring user interaction for exploitation. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
1.00\(aawb.10\)c0CPE matchmatch criteria
cpe:2.3:o:zyxel:nbg6816_firmware:1.00\(aawb.10\)c0:*:*:*:*:*:*:*
< 1.00\(abcs.11\)c0CPE matchmatch criteria
cpe:2.3:o:zyxel:nbg6817_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.0HIGH

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

Attack Vector
ADJACENT_NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.1
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.44%
Probability of exploitation in next 30 days
EPSS Percentile
36.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0044 is in the 39th percentile among its peer group of 14,875 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 0.1 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

zyxel.com / support/forgery-vulnerabilities-of-select-Armor-home-routers.shtml
Vendor Advisory