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CVE-2026-20307

CRITICALCVSS 9.9/10

Last modified

CVE-2026-20307 is a critical-severity vulnerability rated 9.9/10 on the CVSS scale. A vulnerability in the web-based management interface of 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 at least low-privileged administrative credentials. This vulnerability is due to insecure deserialization of a user-supplied Java byte stream.

Description

A vulnerability in the web-based management interface of 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 at least low-privileged administrative credentials. This vulnerability is due to insecure deserialization of a user-supplied Java byte stream. An attacker could exploit this vulnerability by sending a crafted serialized Java object to the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary code on the device and 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 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.

Metrics

CVSS 3.1
9.9/10

CVSS:3.1/AV:N/AC:L/PR:L/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-2026-20307?
A vulnerability in the web-based management interface of 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 at least low-privileged administrative credentials. This vulnerability is due to insecure deserialization of a user-supplied Java byte stream. An attacker could exploit this vulnerability by sending a crafted serialized Java object to the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary code on the device and 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 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.
How severe is CVE-2026-20307?
CVE-2026-20307 has a CVSS score of 9.9/10 (CRITICAL severity).
How do I fix CVE-2026-20307?
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