How severe is CVE-2023-4397?

CVE-2023-4397 has a CVSS 3.x base score of 4.4, rated medium severity. It is exploitable over local access with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2023-4397 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (14th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-4397?

CVE-2023-4397 affects Zyxel Zld. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-4397?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2023-4397 published?

CVE-2023-4397 was published on 2023-11-28 and last updated on 2026-06-17.

CVE-2023-4397

CVE-2023-4397 is a medium-severity vulnerability in Zyxel Zld with a CVSS 3.x base score of 4.4. 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-120.

Key facts

Severity: Medium (CVSS 3.x base score 4.4)
EPSS exploit prediction: 0% (14th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Zyxel Zld
Published: 2023-11-28
Last modified: 2026-06-17

Description

A buffer overflow vulnerability in the Zyxel ATP series firmware version 5.37, USG FLEX series firmware version 5.37, USG FLEX 50(W) series firmware version 5.37, and USG20(W)-VPN series firmware version 5.37, could allow an authenticated local attacker with administrator privileges to cause denial-of-service (DoS) conditions by executing the CLI command with crafted strings on an affected device.

Frequently asked questions

What is CVE-2023-4397?: A buffer overflow vulnerability in the Zyxel ATP series firmware version 5.37, USG FLEX series firmware version 5.37, USG FLEX 50(W) series firmware version 5.37, and USG20(W)-VPN series firmware version 5.37, could allow an authenticated local attacker with administrator privileges to cause denial-of-service (DoS) conditions by executing the CLI command with crafted strings on an affected device.
How severe is CVE-2023-4397?: CVE-2023-4397 has a CVSS 3.x base score of 4.4, rated medium severity. It is exploitable over local access with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2023-4397 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (14th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-4397?: CVE-2023-4397 affects Zyxel Zld. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-4397?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-4397 published?: CVE-2023-4397 was published on 2023-11-28 and last updated on 2026-06-17.

References

https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-in-firewalls-and-aps

Affected products (1)

cpe:2.3:o:zyxel:zld:5.37:*:*:*:*:*:*:*

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