CVE-2025-20222
Published: 14 August 2025
Summary
CVE-2025-20222 is a high-severity Classic Buffer Overflow (CWE-120) vulnerability in Cisco Secure Firewall (inferred from references). Its CVSS base score is 8.6 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked in the top 39.0% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SC-5 (Denial-of-service Protection) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2025-20222 is a denial-of-service (DoS) vulnerability in the RADIUS proxy feature for the IPsec VPN component of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software. The issue stems from improper processing of IPv6 packets, which could allow an unauthenticated, remote attacker to trigger a device reload. It has a CVSS v3.1 base score of 8.6 (AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H) and is associated with CWE-120 (Buffer Copy without Checking Size of Input).
An unauthenticated, remote attacker can exploit this vulnerability by sending crafted IPv6 packets over an IPsec VPN connection to an affected device. Successful exploitation results in a reload of the device, causing a temporary DoS condition that disrupts network traffic processing until the device reboots.
The Cisco Security Advisory at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fp2k-IPsec-dos-tjwgdZCO details affected software versions, workarounds, and available patches for mitigation. Security practitioners should consult the advisory for specific upgrade recommendations and configuration guidance to address the vulnerability.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-24847
Vulnerability details
A vulnerability in the RADIUS proxy feature for the IPsec VPN feature of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of…
more
service (DoS) condition. This vulnerability is due to improper processing of IPv6 packets. An attacker could exploit this vulnerability by sending IPv6 packets over an IPsec VPN connection to an affected device. A successful exploit could allow the attacker to trigger a reload of the device, resulting in a DoS condition.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Direct match to application/system exploitation causing DoS via crafted remote packets on a public-facing VPN service.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Timely flaw remediation through vendor patches directly addresses the improper IPv6 packet processing vulnerability causing device reloads in Cisco ASA/FTD IPsec VPN RADIUS proxy.
Denial-of-service protection limits the impact of crafted IPv6 packets over IPsec VPN that trigger device reloads.
Information input validation on IPv6 packets mitigates the buffer copy without size check (CWE-120) in the RADIUS proxy feature.