PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-20186 Cisco CVE debrief

CVE-2026-20186 is a critical vulnerability in Cisco Identity Services Engine (ISE) that allows authenticated remote attackers to execute arbitrary commands on the underlying operating system of an affected device. To exploit this vulnerability, the attacker must have at least Read Only Admin credentials. This vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected device. A successful exploit could allow the attacker to obtain user-level access to the underlying operating system and then elevate privileges to root. In single-node ISE deployments, successful exploitation of these vulnerabilities could cause the affected ISE node to become unavailable, resulting in a denial of service (DoS) condition. In that condition, endpoints that have not already authenticated would be unable to access the network until the node is restored.

Vendor
Cisco
Product
Cisco Identity Services Engine Software
CVSS
CRITICAL 9.9
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-15
Original CVE updated
2026-06-29
Advisory published
2026-04-15
Advisory updated
2026-06-29

Who should care

Organizations using Cisco Identity Services Engine (ISE) should be aware of this critical vulnerability. Specifically, administrators of ISE deployments, security teams, and IT professionals responsible for Cisco ISE maintenance and security should prioritize patching or mitigating this vulnerability to prevent potential exploitation.

Technical summary

The vulnerability, CVE-2026-20186, is a result of insufficient validation of user-supplied input in Cisco ISE. An authenticated remote attacker with at least Read Only Admin credentials can exploit this vulnerability by sending a crafted HTTP request to an affected device. Successful exploitation allows the attacker to execute arbitrary commands on the underlying operating system, potentially leading to a denial of service (DoS) condition in single-node deployments. The Common Vulnerability Scoring System (CVSS) score for this vulnerability is 9.9, indicating a critical severity level.

Defensive priority

This vulnerability has a high defensive priority due to its critical severity score of 9.9 and the potential for significant impact on affected systems. Immediate action is recommended to patch or mitigate this vulnerability.

Recommended defensive actions

  • Apply patches or updates provided by Cisco to affected ISE versions.
  • Implement additional monitoring and logging to detect potential exploitation attempts.
  • Restrict access to Cisco ISE administrative interfaces to minimize the attack surface.
  • Conduct a thorough review of Cisco ISE configurations and credentials to ensure they are secure and up-to-date.
  • Consider implementing compensating controls, such as network segmentation or access controls, to limit the potential impact of exploitation.

Evidence notes

The CVE-2026-20186 vulnerability is documented in the Cisco Security Advisory and the National Vulnerability Database (NVD). Cisco has provided a detailed description of the vulnerability, its impact, and recommended mitigation strategies. The NVD provides additional information on the vulnerability, including its CVSS score and vector.

Official resources

This article is AI-assisted and based on the supplied source corpus.