A vulnerability in the egress packet processing functionality of the Cisco StarOS operating system for Cisco Aggregation Services Router (ASR) 5700 Series devices and Virtualized Packet Core (VPC) System Software could allow an unauthenticated, remote attacker to cause an interface on the device to cease forwarding packets. The device may need to be manually reloaded to clear this Interface Forwarding Denial of Service condition. The vulnerability is due to the failure to properly check that the length of a packet to transmit does not exceed the maximum supported length of the network interface card (NIC). An attacker could exploit this vulnerability by sending a crafted IP packet or a series of crafted IP fragments through an interface on the targeted device. A successful exploit could allow the attacker to cause the network interface to cease forwarding packets. This vulnerability could be triggered by either IPv4 or IPv6 network traffic. This vulnerability affects the following Cisco products when they are running the StarOS operating system and a virtual interface card is installed on the device: Aggregation Services Router (ASR) 5700 Series, Virtualized Packet Core-Distributed Instance (VPC-DI) System Software, Virtualized Packet Core-Single Instance (VPC-SI) System Software. Cisco Bug IDs: CSCvf32385.
| Software | From | Fixed in |
|---|---|---|
| cisco / staros | 21.0.v0.65819 | 21.0.v0.65819.x |
| cisco / staros | 21.0.v4 | 21.0.v4.x |
| cisco / staros | 21.1.v6 | 21.1.v6.x |
| cisco / staros | 21.3.1 | 21.3.1.x |
| cisco / staros | 21.4.0 | 21.4.0.x |
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.