Cisco Security Advisory
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CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H/E:X/RL:X/RC:X
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Multiple vulnerabilities in Cisco Secure Firewall Management Center (FMC) Software could allow a remote attacker to gain root access and perform session forgery or session impersonation.
For more information about these vulnerabilities, see the Details section of this advisory.
Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc2-multivulns-HXgcqRGThis 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 Secure Firewall products, see Cisco Secure Firewall Adaptive Security Appliance Software, Secure Firewall Threat Defense Software, and Secure Firewall Management Center Software Hardening Release: September 2026.
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Vulnerable Products
These vulnerabilities affect Cisco Secure FMC Software, 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 these vulnerabilities.
Cisco has confirmed that these vulnerabilities do not affect the following Cisco products:
- Secure Firewall Adaptive Security Appliance (ASA) Software
- Secure Firewall Threat Defense (FTD) Software
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The vulnerabilities are not dependent on one another. Exploitation of one of the vulnerabilities is not required to exploit another vulnerability. In addition, a software release that is affected by one of the vulnerabilities may not be affected by the other vulnerabilities.
Details about the vulnerabilities are as follows:
CVE-2026-76420: Cisco Secure FMC Software Peer Impersonation Vulnerability
A vulnerability in the internal configuration of the Apache JServ Protocol (AJP) connector for Cisco Secure FMC Software could allow an unauthenticated, remote attacker to impersonate a peer device.
This vulnerability is due to incorrect initialization of encryption parameters for the AJP connector at boot time. An attacker could exploit this vulnerability by sending crafted packets to the AJP connector. A successful exploit could allow the attacker to execute commands as root and gain full control over the FMC REST APIs on the affected device.
Note: This vulnerability can be exploited only if the valid sftunnel connection between Cisco Secure FMC Software and Cisco Secure FTD Software is down.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwu27279
CVE ID: CVE-2026-76420
Security Impact Rating (SIR): Critical
CVSS Base Score: 9.0
CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:HCVE-2026-76412: Cisco Secure FMC Software Privilege Escalation to root Vulnerability
A vulnerability in the remote diagnostics debugger of Cisco Secure FMC Software could allow an authenticated, remote attacker to enable the remote diagnostics debugger service.
This vulnerability is due to an error when checking the privilege level of a user who is invoking remote diagnostics. An attacker could exploit this vulnerability by authenticating to the device, either through the web-based management interface or the REST API, and using the remote diagnostics debugger to grant a user elevated privileges. A successful exploit could allow the attacker to elevate privileges to root.
Notes:
- To exploit this vulnerability, the attacker must have valid user credentials on the affected device.
- The CVSSv3.1 Attack Complexity is High due to the multistage process required to fully exploit this vulnerability.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwu12566
CVE ID: CVE-2026-76412
Security Impact Rating (SIR): High
CVSS Base Score: 8.5
CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:HCVE-2026-76413: Cisco Secure FMC Single Sign-On Token Forgery Account Vulnerability
A vulnerability in Cisco Adaptive Security Device Manager (ASDM) single sign-on (SSO) handler for Cisco Secure FMC Software could allow an unauthenticated, remote attacker to log in as the Cisco ASDM administrator user.
This vulnerability is due to improper management of the Cisco ASDM SSO token. An attacker could exploit this vulnerability by performing session token forgery techniques. A successful exploit could allow the attacker to log in as the administrator user and, by repeating this action, keep legitimate administrators locked out of the ASDM indefinitely.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwu16965
CVE ID: CVE-2026-76413
Security Impact Rating (SIR): High
CVSS Base Score: 8.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
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There are no workarounds that address these vulnerabilities.
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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 these vulnerabilities and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.
Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software
To help customers determine their exposure to vulnerabilities in Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software, Cisco provides the Cisco Software Checker. This tool identifies any Cisco security advisories that impact a specific software release and the earliest release that fixes the vulnerabilities that are described in each advisory (“First Fixed”). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities that are described in all the advisories that the Software Checker identifies (“Combined First Fixed”).
To use the tool, go to the Cisco Software Checker page and follow the instructions. Alternatively, use the following form to search for vulnerabilities that affect a specific software release. To use the form, follow these steps:
- Choose which advisories the tool will search—all advisories, only advisories with a Critical or High Security Impact Rating (SIR), or only this advisory.
- Choose the appropriate software.
- Choose the appropriate platform.
- Enter a release number—for example, 9.20.3.4 for Cisco Secure Firewall ASA Software or 7.4.2 for Cisco Secure FTD Software.
- Click Check.
Additional Resources
For help determining the best Cisco Secure Firewall ASA, Secure FMC, or Secure FTD Software release, see the following Recommended Releases documents. If a security advisory recommends a later release, Cisco recommends following the advisory guidance.
Cisco Secure Firewall ASA Compatibility
Cisco Secure Firewall ASA Upgrade Guide
Cisco Secure Firewall Threat Defense Compatibility Guide
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The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.
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Cisco would like to thank Nicholas Michael Kloster, an independent security researcher, for reporting these vulnerabilities.
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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
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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.