CVE-2025-20202 is a high-severity vulnerability affecting Cisco IOS XE Wireless Controller Software, specifically related to the processing of Cisco Discovery Protocol (CDP) neighbor reports by wireless controllers managing access points (APs). The root cause is insufficient input validation of the length value in buffer access when handling CDP packets sent to APs. An unauthenticated attacker located adjacent to the network (i.e., within the same broadcast domain or local network segment) can exploit this vulnerability by sending a specially crafted CDP packet to an AP. This crafted packet triggers improper buffer handling in the wireless controller software, causing an unexpected reload or crash of the wireless controller device. The result is a denial of service (DoS) condition that disrupts the wireless network managed by the affected controller. The vulnerability affects a wide range of Cisco IOS XE software versions, spanning multiple releases from 16.10.1 through 17.15.1b, indicating a long-standing issue across many deployed versions. The CVSS 3.1 base score is 7.4, reflecting a high severity with the vector AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H, meaning the attack requires adjacent network access but no privileges or user interaction, and impacts availability with a scope change. No known exploits are currently reported in the wild, but the vulnerability's nature and ease of exploitation make it a significant risk for wireless infrastructure relying on Cisco controllers. The vulnerability does not impact confidentiality or integrity but can cause significant operational disruption by taking down wireless network services.

For European organizations, this vulnerability poses a critical risk to wireless network availability, especially in environments heavily dependent on Cisco wireless infrastructure such as enterprises, educational institutions, healthcare providers, and government agencies. A successful exploit can cause wireless controllers to reload unexpectedly, leading to network outages, loss of connectivity for wireless clients, and potential disruption of business-critical applications relying on Wi-Fi access. This can degrade productivity, impact customer-facing services, and potentially affect safety-critical systems in sectors like healthcare or manufacturing. Since the attack requires only adjacent network access and no authentication, attackers could exploit this vulnerability from within compromised internal networks or via malicious insiders. The widespread use of Cisco IOS XE in Europe means many organizations could be affected, particularly those with large-scale wireless deployments. The scope change in the CVSS vector indicates that the impact extends beyond a single component, potentially affecting multiple network segments managed by the controller. Although no data breach or integrity compromise is indicated, the availability impact alone can have serious operational and financial consequences.

1. Immediate patching: Organizations should prioritize applying Cisco's security updates or patches addressing CVE-2025-20202 as soon as they become available. Given the extensive list of affected versions, verifying the exact software version in use and upgrading to a fixed release is critical. 2. Network segmentation: Limit access to wireless controllers and APs by segmenting management and wireless traffic from general user networks to reduce the attack surface. 3. Control CDP traffic: Implement filtering or rate limiting of CDP packets on network segments where wireless APs reside to prevent maliciously crafted CDP packets from reaching the devices. 4. Monitor network traffic: Deploy intrusion detection or prevention systems (IDS/IPS) tuned to detect anomalous or malformed CDP packets indicative of exploitation attempts. 5. Access control: Restrict physical and logical access to network segments hosting wireless infrastructure to trusted personnel only. 6. Incident response readiness: Prepare for potential DoS incidents by having failover wireless controllers or backup connectivity options to maintain network availability during remediation. 7. Vendor communication: Stay informed through Cisco advisories and coordinate with Cisco support for guidance and updates on patches or workarounds.