CVE-2018-15399
MediumCVSS 6.8Exploitation Probability (EPSS)
High risk77th percentile - higher than 77% of all known CVEs
Summary
A vulnerability in the TCP syslog module of Cisco ASA and FTD Software could allow an unauthenticated, remote attacker to exhaust 1550-byte buffers on an affected device, causing a DoS condition. The issue is due to a missing boundary check in an internal function. An attacker could exploit this by performing a man-in-the-middle attack between the device and its TCP syslog server and modifying TCP headers.
Risk Assessment
The risk includes disruption of all TCP-based features such as AnyConnect SSL VPN, clientless SSL VPN, and management connections, potentially impacting service availability.
Recommendation
It is recommended to upgrade ASA/FTD software to a patched version and monitor TCP syslog traffic for anomalies.
Other vulnerabilities in Cisco Adaptive Security Appliance Software
See all- CVE-2022-20713Medium
A vulnerability in the VPN web client services component of Cisco ASA and FTD Software could allow an unauthenticated, remote attacker to conduct browser-based attacks against users. The issue is due to improper validation of input passed to the component before being returned to the browser. An attacker could exploit this by persuading a user to visit a website that sends malicious requests to an affected device with VPN web services enabled.
- CVE-2020-3555Medium
A vulnerability in the SIP inspection process of Cisco ASA and FTD Software could allow an unauthenticated, remote attacker to cause a crash and reload of an affected device, resulting in a DoS condition. The issue is due to a watchdog timeout and crash during cleanup of threads associated with a SIP connection being deleted. An attacker could exploit this by sending a high rate of crafted SIP traffic.
- CVE-2019-1715Medium
A vulnerability in the DRBG (PRNG) used in Cisco ASA and FTD Software could allow an unauthenticated, remote attacker to cause a cryptographic collision, enabling discovery of the private key of an affected device. The issue is due to insufficient entropy in the DRBG when generating cryptographic keys. An attacker could exploit this by generating many keys and looking for collisions with target devices.
- CVE-2019-1697Medium
A vulnerability in the Lightweight Directory Access Protocol (LDAP) feature implementation in Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The issue is due to improper parsing of LDAP packets. An attacker could send a crafted LDAP packet using Basic Encoding Rules (BER), causing the device to reload.
- CVE-2019-1693Medium
A vulnerability in the WebVPN service of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition. The issue is due to improper management of authenticated sessions in the WebVPN portal. An attacker could authenticate with valid credentials and access a specific URL, causing the device to reload and resulting in temporary DoS.
- CVE-2018-15398Medium
A vulnerability in the per-user-override feature of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass an access control list (ACL) configured for an interface. The issue is due to errors that could occur when constructing and applying per-user-override rules. An attacker could connect to a network through an affected device, potentially accessing resources that would typically be protected by the interface ACL.
Original NVD description (English source)
A vulnerability in the TCP syslog module of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to exhaust the 1550-byte buffers on an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to a missing boundary check in an internal function. An attacker could exploit this vulnerability by establishing a man-in-the-middle position between an affected device and its configured TCP syslog server and then maliciously modifying the TCP header in segments that are sent from the syslog server to the affected device. A successful exploit could allow the attacker to exhaust buffer on the affected device and cause all TCP-based features to stop functioning, resulting in a DoS condition. The affected TCP-based features include AnyConnect SSL VPN, clientless SSL VPN, and management connections such as Secure Shell (SSH), Telnet, and HTTPS.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

