Several vulnerabilities have been discovered in Cisco products, the most serious of which could allow remote code execution. Cisco is a leading technology company known for its networking hardware and software, such as routers and switches, that form the backbone of the Internet and business networks. Successful exploitation of the most severe of these vulnerabilities could allow remote code execution as root, which could lead to complete compromise of the affected device.

The Cisco Product Security Incident Response Team (PSIRT) is aware of an attempted exploitation of CVE-2025-20333 and CVE-2025-20362. A detection guide can be found in the references section further down in this review.

Tactical: Initial access (TA0001):

Technical: Operate a public application (T1190):

• A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to gain unauthenticated access to restricted URL endpoints that would otherwise be inaccessible without authentication. The vulnerability is due to improper validation of user-supplied input in HTTP(S) requests. An attacker could exploit this vulnerability by sending crafted HTTP requests to a targeted web server on a device. A successful exploit could allow the attacker to access a restricted URL without authentication. (CVE-2025-20362)
• A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker to execute arbitrary code on an affected device. The vulnerability is due to improper validation of user-supplied input in HTTP(S) requests. An attacker with valid VPN user credentials could exploit this vulnerability by sending crafted HTTP requests to an affected device. A successful exploit could allow the attacker to execute arbitrary code as root, which could lead to the complete compromise of the affected device. (CVE-2025-20333)
• A vulnerability in the web services of Cisco Secure Firewall Adaptive Security Appliance (ASA), Cisco Secure Firewall Threat Defense (FTD), Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow an unauthenticated, remote attacker (Cisco ASA and FTD Software) or an authenticated, remote attacker (Cisco IOS, IOS XE, and IOS XR Software) with low user privileges to execute arbitrary code on an affected device. This vulnerability is due to improper validation of user-supplied input in HTTP requests. An attacker could exploit this vulnerability by sending crafted HTTP requests to a targeted web service on an affected device after obtaining additional information about the system, overcoming exploit mitigations, or both. A successful exploit could allow the attacker to execute arbitrary code as root, which could lead to the complete compromise of the affected device. (CVE-2025-20363)

Successful exploitation of the most severe of these vulnerabilities could allow remote code execution as root, which could lead to complete compromise of the affected device.

We recommend that the following actions be taken:

• Apply appropriate updates provided by Cisco or other vendors that use this software to vulnerable systems immediately after appropriate testing. (M1051: Update software)
• Backup 7.1: Establish and maintain a vulnerability management process: Establish and maintain a documented vulnerability management process for company assets. Review and update documentation annually or when significant changes within the business occur that could impact this protection.
• Safeguard 7.2: Establish and maintain a remediation process: Establish and maintain a risk-based remediation strategy, documented in a remediation process, with monthly or more frequent reviews.
• Backup 7.4: Perform automated application patch management: Perform application updates on enterprise assets with automated patch management on a monthly or more frequent basis.
• Backup 7.5: Perform automated vulnerability scans of internal company assets: Perform automated vulnerability scans of internal company assets on a quarterly or more frequent basis. Perform authenticated and unauthenticated scans using a SCAP-compliant vulnerability scanning tool.
• Backup 7.7: Fix detected vulnerabilities: Remediate detected vulnerabilities in software through processes and tools on a monthly or more frequent basis, depending on the remediation process.
• Backup 12.1: Ensure network infrastructure is up to date: Make sure the network infrastructure is kept up to date. Example implementations include running the latest stable version of the software and/or using currently supported Network as a Service (NaaS) offerings. Review software versions monthly, or more frequently, to verify software support.
• Backup 18.1: Establish and maintain a penetration testing program: Establish and maintain a penetration testing program appropriate to the size, complexity and maturity of the company. Penetration testing program characteristics include scope, such as network, web application, application programming interface (API), hosted services, and physical premises controls; frequency; limitations, such as acceptable hours and excluded types of attacks; contact details; corrective actions, such as how results will be communicated internally; and retrospective requirements.
• Backup 18.2: Perform periodic external penetration tests: Perform periodic external penetration testing based on program requirements, at least annually. External penetration testing should include reconnaissance of the business and environment to detect actionable information. Penetration testing requires specialist skills and experience and should be carried out by a qualified party. The test can be carried out in a transparent box or an opaque box.
• Backup 18.3: Results of corrective penetration tests: Remediate penetration test results based on company policy for scoping and prioritization of remedial actions.

• Apply the principle of least privilege to all systems and services. Run all software as an unprivileged user (without administrative privileges) to lessen the effects of a successful attack. (M1026: Privileged account management)
• Backup 4.7: Manage default accounts on company assets and software: Manage default accounts on company assets and software, such as root, administrator, and other preconfigured vendor accounts. Example implementations may include: disabling default accounts or rendering them unusable.
• Backup 5.5: Establish and maintain an inventory of service accounts: Establish and maintain an inventory of service accounts. The inventory must at a minimum contain the service owner, review date and purpose. Perform service account reviews to verify that all active accounts are authorized, on a recurring schedule at least quarterly or more frequently.

• Vulnerability scanning is used to find potentially exploitable software vulnerabilities for remediation. (M1016: Vulnerability Analysis)
• Backup 16.13: Perform application penetration testing: Perform application penetration testing. For mission-critical applications, authenticated penetration testing is better suited to detecting business logic vulnerabilities than code analysis and automated security testing. Penetration testing relies on the tester's ability to manually manipulate an application as an authenticated and unauthenticated user.

• Architect sections of the network to isolate critical systems, functions or resources. Use physical and logical segmentation to prevent access to potentially sensitive systems and information. Use a DMZ to contain all Internet-accessible services that should not be exposed from the internal network. Configure separate virtual private cloud (VPC) instances to isolate critical cloud systems. (M1030: Network segmentation)
• Backup 12.2: Establish and maintain a secure network architecture: Establish and maintain a secure network architecture. A secure network architecture must at a minimum take into account segmentation, least privilege and availability.

• Use features to detect and block conditions that could lead to or indicate the occurrence of a software exploit. (M1050: Exploit Protection)
• Backup 10.5: Enable anti-exploitation features: Enable anti-exploitation features on company assets and software where possible, such as Microsoft Data Execution Prevention (DEP), Windows Defender Exploit Guard (WDEG) or Apple System Integrity Protection (SIP) and Gatekeeper.