CVE-2019-1721 Explained : Impact and Mitigation
Learn about CVE-2019-1721, a high-impact vulnerability in Cisco Expressway Series and Cisco TelePresence Video Communication Server that allows an attacker to cause a denial of service situation by exploiting a flaw in the phone book feature.
A security flaw in the phone book feature of Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS) can lead to a denial of service (DoS) situation. This vulnerability, with a CVSS base score of 7.7, allows an authenticated remote attacker to exhaust CPU resources by sending a specially crafted XML payload.
Understanding CVE-2019-1721
This CVE involves a vulnerability in Cisco Expressway Series and Cisco TelePresence Video Communication Server that can be exploited by an authenticated remote attacker to cause a DoS situation by manipulating XML input.
What is CVE-2019-1721?
The flaw in the phone book feature of Cisco Expressway Series and Cisco TelePresence Video Communication Server allows an attacker to send a crafted XML payload via SIP message, causing CPU usage to reach 100% and resulting in a DoS condition.
The Impact of CVE-2019-1721
The vulnerability has a high impact, with a CVSS base score of 7.7. If successfully exploited, it can lead to a denial of service situation on the affected system, requiring manual intervention to recover.
Technical Details of CVE-2019-1721
This section provides detailed technical information about the vulnerability.
Vulnerability Description
The vulnerability is caused by the mishandling of XML input in the phone book feature of Cisco Expressway Series and Cisco TelePresence Video Communication Server.
Affected Systems and Versions
- Product: Cisco TelePresence Video Communication Server (VCS)
- Vendor: Cisco
- Versions Affected: < X12.5.1 (unspecified/custom version)
Exploitation Mechanism
- An authenticated remote attacker sends a specially crafted XML payload via SIP message to the affected device.
- Successful exploitation leads to 100% CPU usage, causing a DoS condition.
Mitigation and Prevention
Protecting systems from CVE-2019-1721 requires immediate actions and long-term security practices.
Immediate Steps to Take
- Apply the fixes released by Cisco in X12.5.1 and later versions.
- Monitor system performance for any unusual CPU spikes.
Long-Term Security Practices
- Regularly update and patch systems to prevent known vulnerabilities.
- Implement network segmentation to limit the impact of potential attacks.
Patching and Updates
- Ensure all systems are updated with the latest security patches from Cisco.