CVE-2025-20182 is a high-severity vulnerability affecting multiple Cisco products, including Cisco Adaptive Security Appliance (ASA) Software, Cisco Firepower Threat Defense (FTD) Software, Cisco IOS Software, and Cisco IOS XE Software. The vulnerability arises from an out-of-bounds write condition in the processing of Internet Key Exchange version 2 (IKEv2) protocol messages. Specifically, the root cause is insufficient input validation when handling crafted IKEv2 traffic. An unauthenticated, remote attacker can exploit this flaw by sending specially crafted IKEv2 packets to an affected device, triggering an out-of-bounds write that causes the device to reload unexpectedly. This results in a denial of service (DoS) condition, disrupting network security functions and potentially causing network outages. The vulnerability affects a wide range of software versions, spanning many releases of Cisco ASA and related software, indicating a long-standing and broadly deployed issue. The CVSS v3.1 base score is 8.6, reflecting the vulnerability's high impact on availability (DoS) with no required privileges or user interaction, and network attack vector. The scope is changed (S:C), meaning the vulnerability affects components beyond the initially vulnerable component, potentially impacting the entire device. No known exploits are currently reported in the wild, but the ease of exploitation and the critical role of affected devices in network security make this a significant threat. Cisco has not listed patch links in the provided data, so organizations must monitor Cisco advisories closely for updates and patches.

For European organizations, the impact of CVE-2025-20182 can be substantial. Cisco ASA and related products are widely used in enterprise and service provider networks across Europe for firewalling, VPN termination, and intrusion prevention. A successful exploit could cause critical network security devices to crash and reload, leading to temporary loss of firewall protection, VPN connectivity, and intrusion detection capabilities. This disruption can result in network outages, loss of secure remote access, and increased exposure to other attacks during downtime. Organizations in sectors such as finance, healthcare, government, and critical infrastructure, which rely heavily on continuous network security, could face operational disruptions and compliance issues. Additionally, the vulnerability could be leveraged as part of a larger attack campaign to cause widespread denial of service or to create network instability. Given the unauthenticated, remote exploitability, attackers do not need prior access, increasing the risk of opportunistic attacks from external threat actors.

European organizations should take immediate and specific actions to mitigate this vulnerability beyond generic advice: 1) Inventory and identify all Cisco ASA, FTD, IOS, and IOS XE devices in their network to determine exposure. 2) Monitor Cisco’s official security advisories for patches or firmware updates addressing CVE-2025-20182 and apply them promptly once available. 3) Until patches are applied, implement network-level mitigations such as filtering or rate-limiting IKEv2 traffic from untrusted sources at the perimeter firewall to reduce exposure to crafted packets. 4) Employ intrusion detection/prevention systems (IDS/IPS) with updated signatures to detect anomalous or malformed IKEv2 traffic. 5) Consider segmenting critical network security devices to limit exposure to external networks and reduce attack surface. 6) Conduct regular backups of device configurations and ensure rapid recovery procedures are in place to minimize downtime if a device reload occurs. 7) Engage in proactive threat hunting and monitoring for unusual device reloads or IKEv2 traffic anomalies. 8) Train network operations teams to recognize symptoms of exploitation and respond quickly.