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CVE-2025-20271— Cisco Meraki MX and Z Series AnyConnect VPN with Client Certificate Authentication Denial of Service Vulnerability

Quick assessment

Affected
Cisco Cisco Meraki MX Firmware
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Cisco Meraki Z和Cisco Meraki MX都是美国思科（Cisco）公司的产品。Cisco Meraki Z是一款企业级防火墙、VPN 网关和路由器。Cisco Meraki MX是一款多功能安全和 SD-WAN 企业设备。 Cisco Meraki Z和Cisco Meraki MX存在安全漏洞，该漏洞源于SSL VPN会话建立期间变量初始化错误，可能导致拒绝服务攻击。

CVSS 8.6 · High EPSS 0.54% · P43

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2025-20271

Vulnerability Information
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Vulnerability Title
Cisco Meraki MX and Z Series AnyConnect VPN with Client Certificate Authentication Denial of Service Vulnerability
Source: CVE Program / CVE List V5
Vulnerability Description
A vulnerability in the Cisco AnyConnect VPN server of Cisco Meraki MX and Cisco Meraki Z Series Teleworker Gateway devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the Cisco AnyConnect service on an affected device. This vulnerability is due to variable initialization errors when an SSL VPN session is established. An attacker could exploit this vulnerability by sending a sequence of crafted HTTPS requests to an affected device. A successful exploit could allow the attacker to cause the Cisco AnyConnect VPN server to restart, resulting in the failure of all established SSL VPN sessions and forcing remote users to initiate a new VPN connection and re-authenticate. A sustained attack could prevent new SSL VPN connections from being established, effectively making the Cisco AnyConnect VPN service unavailable for all legitimate users.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
使用未经初始化的变量
Source: CVE Program / CVE List V5
Vulnerability Title
Cisco Meraki Z和Cisco Meraki MX 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Cisco Meraki Z和Cisco Meraki MX都是美国思科（Cisco）公司的产品。Cisco Meraki Z是一款企业级防火墙、VPN 网关和路由器。Cisco Meraki MX是一款多功能安全和 SD-WAN 企业设备。 Cisco Meraki Z和Cisco Meraki MX存在安全漏洞，该漏洞源于SSL VPN会话建立期间变量初始化错误，可能导致拒绝服务攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Cisco Cisco Meraki MX Firmware N/A -

II. Public POCs for CVE-2025-20271

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III. Intelligence Information for CVE-2025-20271

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Same Patch Batch · Cisco · 2025-06-18 · 3 CVEs total

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IV. Related Vulnerabilities

Same product: Cisco Meraki MX Firmware
Same vendor: Cisco
Same weakness: CWE-457

V. Comments for CVE-2025-20271

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