Cisco Security Advisory
Cisco Identity Services Engine Authentication Bypass Vulnerability
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CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:X/RL:X/RC:X
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A vulnerability in an API of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to bypass authentication.
This vulnerability is due to insufficient authentication control on an API endpoint. An attacker could exploit this vulnerability by sending a crafted request to an affected API endpoint. A successful exploit could allow the attacker to gain unauthorized access to the affected device by bypassing the web-based management interface.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ISE-ABP-VNSW7Tn5This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of September 16, 2026, Security Advisories. In addition, for further documentation of improvements and fixes in Cisco Identity Services Engine, see Cisco Identity Services Engine Security Hardening Release: September 2026.
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Vulnerable Products
This vulnerability affects Cisco ISE and Cisco ISE Passive Identity Connector (ISE-PIC), regardless of device configuration.
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
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To confirm any attempted exploitation of this vulnerability, review the access.log and look for suspicious usernames. If the device is part of a distributed deployment, review the logs of each node. The following is a non-exhaustive example of how a suspicious username could be detected in the logs:
admin#show logging application ise-kong/access.log | include dummyuser
To view additional access.log files, collect a support bundle with include debug logs selected, use shared key encryption, and then decrypt and find the access logs at ./ise/logs/apigateway/access.log.
.gz. The presence of any entry in the output may indicate malicious activity. This should be done on every node in the deployment. If malicious activity is suspected, it is strongly recommended to re-image the affected nodes and restore from configuration backup if needed.
Note: Upon successful exploitation of this vulnerability, threat actors may obtain command execution with root privileges. Because of this level of access, evidence of exploitation and indicators of compromise may be removed or hidden by the threat actors. Cisco strongly recommends that administrators cross-check the network logs and the firewall logs outside of the impacted device to identify any potential suspicious activity, including but not limited to unexpected uploads that were initiated from the affected device to external IP addresses or downloads from malicious IP addresses.
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There are no workarounds that address this vulnerability. However, there is a mitigation. To prevent remote exploitation of this vulnerability, use infrastructure access control lists (iACLs) to allow only required management and control plane traffic that is destined to the affected device.
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Cisco considers any workarounds and mitigations (if applicable) to be temporary solutions until an upgrade to a fixed software release is available. To remediate this vulnerability and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.
Fixed Releases
In the following table(s), the left column lists Cisco software releases. The right column indicates whether a release is affected by the vulnerability that is described in this advisory and the first release that includes the fix for this vulnerability. Customers are advised to upgrade to an appropriate fixed software release as indicated in this section.
Cisco ISE or ISE-PIC Release First Fixed Release 3.1 3.1 Patch 12 3.2 3.2 Patch 11 3.3 3.3 Patch 12 3.4 3.4 Patch 7 3.51 3.5 Patch 4 1. Cisco ISE Software Release 3.0 has reached End of Software Maintenance. Customers are advised to migrate to a supported release that includes the fix for this vulnerability.For instructions on upgrading a device, see the Upgrade Guides on the Cisco Identity Service Engine support page.
The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.
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The Cisco PSIRT is aware of active exploitation of this vulnerability. Cisco strongly recommends that customers upgrade to a fixed software release to remediate this vulnerability.
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This vulnerability was found during the resolution of a Cisco Technical Assistance Center (TAC) support case.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
For additional information on Cisco's vulnerability management, disclosure cadence, and software patching strategy, see Cisco's Transition to a Risk-Based Vulnerability Disclosure Model.
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Show LessVersion Description Section Status Date 1.0 Initial public release. - Final 2026-SEP-16
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SOFTWARE DOWNLOADS AND TECHNICAL SUPPORT
The Cisco Support and Downloads page on Cisco.com provides information about licensing and downloads. This page can also display customer device support coverage for customers who use the My Devices tool. Please note that customers may download only software that was procured from Cisco directly or through a Cisco authorized reseller or partner and for which the license is still valid.
Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco Technical Assistance Center (TAC). Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade.
When considering software upgrades, customers are advised to regularly consult the advisories for the relevant Cisco products to determine exposure and a complete upgrade solution. In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
LEGAL DISCLAIMER DETAILS
CISCO DOES NOT MAKE ANY EXPRESS OR IMPLIED GUARANTEES OR WARRANTIES OF ANY KIND, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. WITHOUT LIMITING THE GENERALITY OF THE FOREGOING, CISCO DOES NOT GUARANTEE THE ACCURACY OR COMPLETENESS OF THIS INFORMATION. THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
Copies or summaries of the information contained in this Security Advisory may lack important information or contain factual errors. Customers are advised to visit the Cisco Security Advisories page for the most recent version of this Security Advisory. The Cisco Product Security Incident Response Team (PSIRT) assesses only the affected and fixed release information that is documented in this advisory. See the Cisco Security Vulnerability Policy for more information.