Cisco ISE Authenticated Remote Code Execution via Java Deserialization
CVE-2026-20211 Published on September 16, 2026

Cisco Identity Services Engine Remote Code Execution Vulnerability
A vulnerability in Cisco ISE could allow an authenticated, remote attacker to execute arbitrary commands on the underlying operating system of an affected device. To exploit this vulnerability, the attacker must have valid high-privileged administrative credentials. This vulnerability is due to insecure deserialization of Java objects by the affected software. An attacker could exploit this vulnerability by sending a crafted serialized Java object 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 deployments, successful exploitation of this vulnerability could cause the affected ISE node to become unavailable, resulting in a DoS condition. In that condition, endpoints that have not already authenticated would be unable to access the network until the node is restored.

NVD

Vulnerability Analysis

CVE-2026-20211 can be exploited with network access, and requires user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
HIGH
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
HIGH
Availability Impact:
HIGH

Weakness Type

What is a Marshaling, Unmarshaling Vulnerability?

The application deserializes untrusted data without sufficiently verifying that the resulting data will be valid.

CVE-2026-20211 has been classified to as a Marshaling, Unmarshaling vulnerability or weakness.


Products Associated with CVE-2026-20211

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Cisco Identity Services Engine Software
 

Affected Versions

Cisco Identity Services Engine Software:

Exploit Probability

EPSS
0.56%
Percentile
44.28%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.