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CVE-2026-20237: Improper Input Validation in Cisco Cisco Identity Services Engine Software

0
Critical
VulnerabilityCVE-2026-20237cvecve-2026-20237
Published: 09/16/2026 (09/16/2026, 20:08:20 UTC)
Source: CVE Database V5
Vendor/Project: Cisco
Product: Cisco Identity Services Engine Software

Description

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Identity Services Engine (ISE) and Cisco ISE Passive Identity Connector (ISE-PIC), engineering teams have conducted a comprehensive internal security review. This review resulted in a software hardening release that addresses multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20237 are related to improper input validation issues that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-20.

CVSS v3.1

Score 9.1critical

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Affected software

Cisco

Cisco Identity Services Engine Software

Affected versions
=3.1.0=3.2.0=3.3.0=3.4.0=3.5.0

Cisco

Cisco ISE Passive Identity Connector

Affected versions
=3.2.0=3.1.0=3.3.0=3.4.0=3.5.0

AI-Powered Analysis

Machine-generated threat intelligence

AILast updated: 09/16/2026, 20:33:18 UTC

Technical Analysis

Cisco Identity Services Engine (ISE) and ISE Passive Identity Connector (ISE-PIC) contain multiple improper input validation vulnerabilities grouped under CWE-20. These issues were discovered internally by Cisco engineering teams during a comprehensive security review. The vulnerability affects Cisco ISE Software versions 3.1.0, 3.2.0, 3.3.0, 3.4.0, and 3.5.0. The CVSS v3.1 base score is 9.1, indicating critical severity with network attack vector, low attack complexity, high privileges required, no user interaction, and impacts on confidentiality, integrity, and availability with scope changed.

Potential Impact

Successful exploitation of this vulnerability could allow an attacker with high privileges to cause a complete compromise of the affected Cisco ISE system, impacting confidentiality, integrity, and availability. The critical CVSS score reflects the potential for severe damage to the system and network environment.

Mitigation Recommendations

Cisco has released a software hardening update addressing these vulnerabilities as part of their proactive security commitment. Users should apply the official Cisco patches or updates that fix these issues. Since this is not a cloud service, remediation requires customer action to update affected software versions. Patch status is confirmed by Cisco's internal review and release of a hardening update.

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Technical Details

Data Version
5.2
Assigner Short Name
cisco
Date Reserved
2025-10-08T11:59:15.400Z
Cvss Version
3.1
State
PUBLISHED

Threat ID: 6aaaf94155bf5e2cf51b934f

Added to database: 09/16/2026, 20:17:05 UTC

Last enriched: 09/16/2026, 20:33:18 UTC

Last updated: 09/17/2026, 01:28:54 UTC

Views: 7

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