Cisco ASA Next-Generation Firewall contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
A vulnerability in fragmented traffic processing on Cisco ASA NGFW could allow an unauthenticated, remote attacker to cause a reload of the affected device.
The vulnerability is due to invalid parsing of reassembled packet data. An attacker could exploit this vulnerability by sending fragmented traffic to be processed by one of the ASA NGFW deny policies.
Cisco has confirmed the vulnerability in a security advisory and has released software updates.
The following Cisco products are vulnerable:
Cisco ASA NGFW versions prior to 126.96.36.199
Cisco NGFW versions prior to 188.8.131.52
To exploit this vulnerability, an affected Cisco ASA NGFW, also known as Cisco ASA CX Context-Aware Security in versions prior to 9.1.2, needs a configured policy that denies user traffic. In addition, an attacker may require access to trusted, internal networks to send fragmented traffic to an affected device. These requirements could limit the likelihood of a successful exploit.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.
An unauthenticated, remote attacker could exploit this vulnerability to cause an affected device to reload or stop processing user traffic, resulting in a denial of service (DoS) condition. In addition, if an affected device with a Cisco ASA NGFW module running an affected version of the software is configured in High-Availability (HA) mode, a failover event may occur when the Cisco ASA NGFW reloads or stops forwarding traffic. Repeated exploitation could result in a sustained failover condition of the parent Cisco ASA and lead to a sustained DoS condition.
The vulnerability is due to invalid parsing of reassembled packet data processed by the affected software.
An unauthenticated, remote attacker could exploit this vulnerability by sending fragmented traffic to be processed by one of the ASA NGFW deny policies. If successful, the attacker can cause an affected device to reload or stop processing user traffic, resulting in a DoS condition.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators may consider disabling the Modular Policy Framework (MPF) configuration on the Cisco ASA that is used to direct the user traffic toward the Cisco ASA NGFW. Details on disabling this configuration are in the "Workarounds" section of the security advisory.
Administrators are advised to monitor affected systems.
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via email at email@example.com.
The security vulnerability applies to the following combinations of products.
Cisco ASA CX Context-Aware Security Software
9.0 Base, .1, .1-40, .2, .2-68
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