VDB-254121 · CVE-2023-6764 · GCVE-0-2023-6764

Zyxel ATP/USG FLEX/USG FLEX 50/USG20-VPN IPSec VPN format string

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
8.1	$5k-$25k	1.13

Summaryinfo

A vulnerability was found in Zyxel ATP, USG FLEX, USG FLEX 50 and USG20-VPN. It has been rated as critical. Affected is an unknown function of the component IPSec VPN. Performing a manipulation results in format string. This vulnerability is identified as CVE-2023-6764. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Zyxel ATP, USG FLEX, USG FLEX 50 and USG20-VPN (Network Encryption Software) (version unknown). It has been classified as critical. This affects an unknown function of the component IPSec VPN. The manipulation with an unknown input leads to a format string vulnerability. CWE is classifying the issue as CWE-134. The product uses a function that accepts a format string as an argument, but the format string originates from an external source. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

A format string vulnerability in a function of the IPSec VPN feature in Zyxel ATP series firmware versions from 4.32 through 5.37 Patch 1, USG FLEX series firmware versions from 4.50 through 5.37 Patch 1, USG FLEX 50(W) series firmware versions from 4.16 through 5.37 Patch 1, and USG20(W)-VPN series firmware versions from 4.16 through 5.37 Patch 1 could allow an attacker to achieve unauthorized remote code execution by sending a sequence of specially crafted payloads containing an invalid pointer; however, such an attack would require detailed knowledge of an affected device’s memory layout and configuration.

The weakness was released 02/20/2024. The advisory is shared at zyxel.com. This vulnerability is uniquely identified as CVE-2023-6764 since 12/13/2023. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 01/21/2025).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

Network Encryption Software

Vendor

Zyxel

Name

License

commercial

Website

Vendor: https://www.zyxel.com/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.1
VulDB Meta Temp Score: 8.1

VulDB Base Score: 8.1
VulDB Temp Score: 8.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

CNA Base Score: 8.1
CNA Vector (Zyxel Corporation): 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Format string
CWE: CWE-134 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔍

Timelineinfo

12/13/2023 🔍
02/20/2024 +69 days 🔍
02/20/2024 +0 days 🔍
01/21/2025 +336 days 🔍

Sourcesinfo

Vendor: zyxel.com

Advisory: zyxel.com
Status: Confirmed

CVE: CVE-2023-6764 (🔍)
GCVE (CVE): GCVE-0-2023-6764
GCVE (VulDB): GCVE-100-254121

Entryinfo

Created: 02/20/2024 07:24
Updated: 01/21/2025 20:46
Changes: 02/20/2024 07:24 (48), 01/21/2025 20:46 (16)
Complete: 🔍
Cache ID: 216::103