CVE-2019-15256 Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software IKEv1 Denial of Service Vulnerability
Unauthenticated remote attackers can cause a denial of service by sending malicious IKEv1 traffic to Cisco ASA or FTD devices, exhausting memory and triggering a reload.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2019-15256?
CVE-2019-15256 is a high-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 2 Oct 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in the Internet Key Exchange version 1 (IKEv1) feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to improper management of system memory. An attacker could exploit this vulnerability by sending malicious IKEv1 traffic to an affected device. The attacker does not need valid credentials to authenticate the VPN session, nor does the attacker's source address need to match a peer statement in the crypto map applied to the ingress interface of the affected device. An exploit could allow the attacker to exhaust system memory resources, leading to a reload of an affected device.
Which versions are affected by CVE-2019-15256?
It affects 13 products.
Products include Cisco Adaptive Security Appliance Software, Cisco Asa 5505 Firmware, Cisco Asa 5510 Firmware, Cisco Asa 5512-X Firmware, Cisco Asa 5515-X Firmware, Cisco Asa 5520 Firmware and 7 more.
How do I fix CVE-2019-15256?
No fix has been published for CVE-2019-15256 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2019-15256 being exploited?
There is no known exploitation of CVE-2019-15256 in the wild and no public exploit code.
Other vulnerabilities in Cisco Adaptive Security Appliance Software
- CVE-2025-20333 Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow
- CVE-2016-6366 Cisco Adaptive Security Appliance (ASA) SNMP Buffer Overflow
- CVE-2026-20349 Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection
- CVE-2024-20353 Cisco ASA and FTD Denial of Service
- CVE-2016-6367 Cisco Adaptive Security Appliance (ASA) CLI Remote Code Execution
All Cisco Adaptive Security Appliance Software vulnerabilities
Sources
Also known as GHSA-5p28-46mx-rrvx.