Critical severity · published Sep 16, 2026
CVE-2026-20211
Cisco Identity Services Engine Remote Code Execution Vulnerability
9.1
CVSS
0.8%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.8% · higher than 58% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CI
Cisco Identity Services Engine Software · Cisco
3.1.0; 3.1.0 p1; 3.1.0 p3; 3.1.0 p2; 3.2.0; 3.1.0 p4; +34 more · source: vendor
In the news
VulnerabilityHigh
ZDI-26-717: Cisco Identity Services Engine AlarmMessageDiskQueue Deserialization of Untrusted Data Remote Code Execution Vulnerability
This vulnerability allows remote attackers to execute arbitrary code on affected installations of Cisco Identity Services Engine. Authentication is required to exploit this vulnerability. The ZDI has assigned a CVSS rating of 7.2. The following CVEs are assigned: CVE-2026-20211.
Sep 18, 2026·Zero Day Initiative
Affected product
CI
Cisco Identity Services Engine Software
Cisco
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-20211
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-20211
sec.cloudapps.cisco.com
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-rce-se7bYU57
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