CVE-2026-20211CWE-502insecure-deserialization

CVE-2026-20211

Critical · published September 17, 2026

CVSS v3.1
9.1
EPSS
1%
Percentile
45.7
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
9.1 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00558 · 45.7th percentile
Weakness
CWE-502 · Deserialization of Untrusted Data
Published
2026-09-17T00:17Z
References (1)
EPSS history
Timeline
  • 18 SEP 03:58Z
    EPSS moved — → 1%
    epss
  • 16 SEP 20:04Z
    Cisco Identity Services Engine Remote Code Execution Vulnerability
    cvelistv5