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CVE-2026-20211

CRITICALCVSS 9.1/10

Last modified

CVE-2026-20211 is a critical-severity vulnerability rated 9.1/10 on the CVSS scale. 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.

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.

Metrics

CVSS 3.1
9.1/10

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
CiscoCisco Identity Services Engine Software3.1.0; 3.1.0 p1; 3.1.0 p3; 3.1.0 p2; 3.2.0; 3.1.0 p4; 3.1.0 p5; 3.2.0 p1; 3.1.0 p6; 3.2.0 p2; 3.1.0 p7; 3.3.0; 3.2.0 p3; 3.2.0 p4; 3.1.0 p8; 3.2.0 p5; 3.2.0 p6; 3.1.0 p9; 3.3 Patch 2; 3.3 Patch 1; 3.3 Patch 3; 3.4.0; 3.2.0 p7; 3.3 Patch 4; 3.4 Patch 1; 3.1.0 p10; 3.3 Patch 5; 3.3 Patch 6; 3.4 Patch 2; 3.3 Patch 7; 3.4 Patch 3; 3.5.0; 3.4 Patch 4; 3.3 Patch 8; 3.2 Patch 8; 3.5 Patch 1; 3.3 Patch 9; 3.2 Patch 9; 3.4 Patch 5; 3.5 Patch 3; 3.5 Patch 2; 3.3 Patch 10; 3.3 Patch 11; 3.4 Patch 6; 3.2 Patch 10; 3.1.0 p72; 3.1.0 p11

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-20211?
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.
How severe is CVE-2026-20211?
CVE-2026-20211 has a CVSS score of 9.1/10 (CRITICAL severity).
How do I fix CVE-2026-20211?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST