A severe new vulnerability has been disclosed in Cisco’s Identity Services Engine (ISE), a network access control system used by countless organizations worldwide. According to an advisory from the vendor, this flaw can be exploited remotely and allows attackers to bypass authentication checks entirely. The severity of the issue is reflected in its CVSS score: 10.0 out of 10.
This vulnerability affects ISE versions prior to 3.2(PI1)S, a relatively recent patch level that suggests many organizations are still running outdated software. The impact of this flaw is significant, as it can be used by attackers to gain unauthorized access to an organization’s network. This may seem like a straightforward problem, but the details reveal a more insidious threat.
The vulnerability works by exploiting an authentication bypass weakness in ISE’s cross-domain functionality. In essence, this feature allows different parts of a network to communicate with each other securely. However, when not properly configured, it can be used as a doorway for unauthorized access. Attackers need only find and exploit a vulnerable endpoint on the network, then use the bypass flaw to gain full control.
The scope of this issue is vast. Many major organizations rely on Cisco ISE for their security needs, including large corporations, government agencies, and financial institutions. It’s likely that thousands or even tens of thousands of networks are currently exposed to this threat. Furthermore, the fact that active attacks have already been observed suggests a significant risk exists.
While some may view this vulnerability as an isolated issue, its potential impact should not be underestimated. A successful exploit could grant attackers unfettered access to sensitive data and allow them to move laterally throughout the network undetected. This would give attackers a clear path to further compromise or exfiltrate sensitive information.
Given the severity of this flaw and the widespread use of Cisco ISE, immediate action is required from affected organizations. The first step should be to verify the current version of their ISE software and apply any available patches. This will help mitigate the risk of unauthorized access through this specific vulnerability. Further investigation into network configurations and cross-domain settings may also be necessary to ensure proper security practices are in place.
Organizations must prioritize patching their systems as soon as possible, while also maintaining a heightened state of vigilance for potential attacks. As the threat landscape continues to evolve, staying up-to-date with the latest security patches and best practices is crucial to minimizing risk.
Source: The Hacker News — 2026-09-17