How severe is CVE-2023-35137?

CVE-2023-35137 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2023-35137 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-35137?

CVE-2023-35137 primarily affects Zyxel Nas326 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-35137?

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-2023-35137 published?

CVE-2023-35137 was published on 2023-11-30 and last updated on 2026-06-17.

CVE-2023-35137

CVE-2023-35137 is a high-severity vulnerability in Zyxel Nas326 Firmware with a CVSS 3.x base score of 7.5. 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-287.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Zyxel Nas326 Firmware
Published: 2023-11-30
Last modified: 2026-06-17

Description

An improper authentication vulnerability in the authentication module of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an unauthenticated attacker to obtain system information by sending a crafted URL to a vulnerable device.

Frequently asked questions

What is CVE-2023-35137?: An improper authentication vulnerability in the authentication module of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an unauthenticated attacker to obtain system information by sending a crafted URL to a vulnerable device.
How severe is CVE-2023-35137?: CVE-2023-35137 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2023-35137 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-35137?: CVE-2023-35137 primarily affects Zyxel Nas326 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-35137?: 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-2023-35137 published?: CVE-2023-35137 was published on 2023-11-30 and last updated on 2026-06-17.

References

https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-authentication-bypass-and-command-injection-vulnerabilities-in-nas-products

Affected products (2)

cpe:2.3:o:zyxel:nas326_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:nas542_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Zyxel Nas326 Firmware

CVE-2024-6342 — Critical (CVSS 9.8): **UNSUPPORTED WHEN ASSIGNED** A command injection vulnerability in the export-cgi program of Zyxel NAS326 firmware…
CVE-2024-29974 — Critical (CVSS 9.8): ** UNSUPPORTED WHEN ASSIGNED ** The remote code execution vulnerability in the CGI program “file_upload-cgi” in…
CVE-2024-29973 — Critical (CVSS 9.8): ** UNSUPPORTED WHEN ASSIGNED ** The command injection vulnerability in the “setCookie” parameter in Zyxel NAS326…
CVE-2024-29972 — Critical (CVSS 9.8): ** UNSUPPORTED WHEN ASSIGNED ** The command injection vulnerability in the CGI program "remote_help-cgi" in Zyxel…
CVE-2023-4474 — Critical (CVSS 9.8): The improper neutralization of special elements in the WSGI server of the Zyxel NAS326 firmware version…
CVE-2023-4473 — Critical (CVSS 9.8): A command injection vulnerability in the web server of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542…

All CVEs affecting Zyxel Nas326 Firmware →

Other CWE-287 (Improper Authentication) vulnerabilities

CVE-2026-45480 — Critical (CVSS 10.0): Improper authentication in Azure Active Directory allows an unauthorized attacker to elevate privileges over a network.
CVE-2026-46389 — Critical (CVSS 10.0): UDS Identity Config builds the Keycloak configuration image (realm, plugins, theme, truststore, JARs) consumed by UDS…
CVE-2026-10611 — Critical (CVSS 10.0): An authentication bypass vulnerability exists in MISP when LDAP mixed authentication is enabled with OTP enforcement.…
CVE-2026-47280 — Critical (CVSS 10.0): Improper authentication in Azure Resource Manager (ARM) allows an unauthorized attacker to elevate privileges over a…
CVE-2026-42822 — Critical (CVSS 10.0): Improper authentication in Azure Local Disconnected Operations allows an unauthorized attacker to elevate privileges…
CVE-2026-20182 — Critical (CVSS 10.0): May 2026: This security advisory provides the details and fix information for a vulnerability that was discovered and…

Browse all CWE-287 (Improper Authentication) vulnerabilities →