How severe is CVE-2021-35028?

CVE-2021-35028 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over an adjacent network with high attack complexity, requires high privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-35028 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-35028?

CVE-2021-35028 affects Zyxel Zywall Vpn2s Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-35028?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-35028 published?

CVE-2021-35028 was published on 2021-09-29 and last updated on 2026-06-17.

CVE-2021-35028

CVE-2021-35028 is a high-severity vulnerability in Zyxel Zywall Vpn2s Firmware with a CVSS 3.x base score of 7.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-78.

Key facts

Severity: High (CVSS 3.x base score 7.3)
CVSS v2: 7.2
EPSS exploit prediction: 0% (21st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-78
Affected product: Zyxel Zywall Vpn2s Firmware
Published: 2021-09-29
Last modified: 2026-06-17

Description

A command injection vulnerability in the CGI program of the Zyxel VPN2S firmware version 1.12 could allow an authenticated, local user to execute arbitrary OS commands.

Frequently asked questions

What is CVE-2021-35028?: A command injection vulnerability in the CGI program of the Zyxel VPN2S firmware version 1.12 could allow an authenticated, local user to execute arbitrary OS commands.
How severe is CVE-2021-35028?: CVE-2021-35028 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over an adjacent network with high attack complexity, requires high privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-35028 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-35028?: CVE-2021-35028 affects Zyxel Zywall Vpn2s Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-35028?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-35028 published?: CVE-2021-35028 was published on 2021-09-29 and last updated on 2026-06-17.

References

https://www.zyxel.com/support/Zyxel_security_advisory_for_directory_traversal_and_command_injection_vulnerabilities_of_VPN2S_Firewall.shtml

Affected products (1)

cpe:2.3:o:zyxel:zywall_vpn2s_firmware:1.12\(abln.0\)c0:*:*:*:*:*:*:*

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