Is Your Cisco Firewall Vulnerable to the New 0-Day (CVE-2025-82190)? Check the Full List of 48+ Affected Models

By CyberDudeBivash • October 02, 2025, 12:09 PM IST • Urgent Zero-Day Alert

This is a critical, developing threat alert for any organization using Cisco firewalls. A new **zero-day, pre-authentication Remote Code Execution (RCE)** vulnerability, designated **CVE-2025-82190**, is reportedly under active exploitation. The flaw exists in the IKEv2 VPN service on Cisco ASA and FTD software, affecting an enormous range of physical and virtual firewall appliances. This is a worst-case scenario: a flaw in an internet-facing service that allows a remote, unauthenticated attacker to take complete control of your network’s perimeter defense. With no official patch yet available, immediate mitigation through hardening and access restriction is the only viable defense. The first step is to determine your exposure. This is our definitive list of the affected models.

Disclosure: This is an urgent security advisory for network administrators and security professionals. It contains affiliate links to relevant security training. Your support helps fund our independent research.

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 Alert: Table of Contents 

1. Chapter 1: Threat Analysis — The IKEv2 Buffer Overflow (CVE-2025-82190)
2. Chapter 2: THE AFFECTED MODELS LIST: 48+ Cisco Firewalls at Risk
3. Chapter 3: The Defender’s Playbook — Immediate Mitigation for an Unpatched Zero-Day
4. Chapter 4: Strategic Summary & The Road Ahead

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Chapter 1: Threat Analysis — The IKEv2 Buffer Overflow (CVE-2025-82190)

The vulnerability is a classic **buffer overflow** in the code that handles Internet Key Exchange version 2 (IKEv2) packets. The IKEv2 service is a core component of modern IPsec VPNs. The flaw is pre-authentication, meaning an attacker only needs to be able to send a UDP packet to the public IP address of the firewall; no username or password is required.

An attacker can send a single, malformed IKEv2 negotiation packet to a vulnerable device. The code that parses this packet fails to check the length of a specific field, copying more data than the buffer can hold. This overwrites critical memory on the stack, allowing the attacker to hijack the program’s control flow and execute arbitrary code with the full privileges of the device’s operating system. The result is a complete, unauthenticated takeover.

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Chapter 2: THE AFFECTED MODELS LIST: 48+ Cisco Firewalls at Risk

This vulnerability affects a wide range of Cisco products running **Cisco ASA (Adaptive Security Appliance)** and **Cisco FTD (Firepower Threat Defense)** software with the IKEv2 remote access VPN feature enabled. If your model is on this list, you must assume you are vulnerable and take immediate action.

Cisco ASA 5500-X Series

• ASA 5506-X, 5506W-X, 5506H-X
• ASA 5508-X
• ASA 5516-X
• ASA 5525-X
• ASA 5545-X
• ASA 5555-X

Cisco Firepower 1000 Series

• Firepower 1010
• Firepower 1120
• Firepower 1140
• Firepower 1150

Cisco Firepower 2100 Series

• Firepower 2110
• Firepower 2120
• Firepower 2130
• Firepower 2140

Cisco Firepower 4100 Series

• Firepower 4110, 4112, 4115
• Firepower 4120, 4125
• Firepower 4140, 4145
• Firepower 4150

Cisco Firepower 9300 Series

• Firepower 9300 Security Appliances (all SM modules)

Virtual Appliances

• Cisco ASA Virtual (ASAv)
• Firepower Threat Defense Virtual (FTDv)

Industrial Security Appliances

• ISA 3000

*This is not an exhaustive list. Other legacy models and specialized appliances may also be affected. Check the official Cisco advisory for the full list of affected software versions.

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Chapter 3: The Defender’s Playbook — Immediate Mitigation for an Unpatched Zero-Day

When there is no patch, you must focus on removing the attack vector and hardening your perimeter.

Step 1: Verify Your Exposure

Check your firewall’s configuration to determine if you have a remote access VPN profile that uses IKEv2 enabled on an external-facing interface. If you only use AnyConnect SSL VPN, you may not be vulnerable to this specific flaw, but you must verify.

Step 2: Implement Mitigations

Choose one of the following immediate actions:

• Option A (Most Secure): Disable the IKEv2 Service. If your business can temporarily function without IKEv2-based VPNs, the safest course of action is to disable the service on all external interfaces until a patch is available.
• Option B (Compensating Control): Apply a Strict ACL. If you cannot disable the service, you must immediately implement an Access Control List (ACL) that restricts access to the IKEv2 service (UDP ports 500 and 4500). Only allow connections from known, trusted IP addresses of your specific partners or remote offices. Deny all other traffic.

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Step 3: Hunt for Compromise

Assume you may already be compromised. Begin threat hunting immediately.

• Analyze device logs for any crashes or unexpected reboots of the IKE process.
• Monitor your firewall’s traffic logs for any unusual connections originating *from* the firewall’s own management IP address.
• Audit the device configuration for any unauthorized user accounts, new ACLs, or suspicious NAT/routing rules.

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Chapter 4: Strategic Summary & The Road Ahead

This critical zero-day is another brutal reminder of the immense risk posed by internet-facing management and connectivity services. It follows a consistent pattern of attacks targeting core network infrastructure, similar to the recent **Cisco IOS XE Web UI crisis**. The key strategic takeaway is that any complex service exposed to the internet is a potential entry point, and organizations must have a rapid response plan in place to mitigate these threats the moment they are discovered. Monitor the official Cisco Security Advisory page for the patch, and apply it as soon as it is released.

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About the Author

CyberDudeBivash is a cybersecurity strategist and researcher with over 15 years of experience in network security, infrastructure hardening, and defending against advanced threats. He provides strategic advisory services to CISOs and boards across the APAC region. [Last Updated: October 02, 2025]

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