CVE-2026-20341: Deserialization of Untrusted Data in Cisco Cisco Secure Firewall Management Center (FMC)
A vulnerability in the sftunnel inter-device communication protocol of Cisco Secure FMC Software could allow an authenticated, remote attacker to obtain root privileges. This vulnerability is due to unsecured deserialization of untrusted data over the sftunnel management connection. An attacker could exploit this vulnerability by sending crafted sftunnel remote procedure calls (RPCs). A successful exploit could allow the attacker to gain root privileges on a device that is running Cisco Secure FMC Software and its high-availability peer. To exploit this vulnerability, the attacker must have valid administrative credentials on a managed Cisco FTD device.
AI Analysis
Technical Summary
This vulnerability arises from unsecured deserialization of untrusted data over the sftunnel management connection in Cisco Secure FMC software. An attacker with valid administrative credentials on a managed Cisco FTD device can exploit this by sending crafted sftunnel remote procedure calls (RPCs), potentially gaining root privileges on the FMC device and its high-availability peer. The vulnerability affects numerous specific versions of Cisco Secure FMC software as listed. 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.
Potential Impact
Successful exploitation allows an authenticated remote attacker with administrative credentials on a managed Cisco FTD device to obtain root privileges on the Cisco Secure FMC device and its high-availability peer. This can lead to full system compromise, including complete control over the firewall management infrastructure.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch or official fix information is provided, organizations should monitor Cisco advisories for updates. Given the requirement for valid administrative credentials, restricting and monitoring administrative access to managed Cisco FTD devices is advisable until a fix is available.
CVE-2026-20341: Deserialization of Untrusted Data in Cisco Cisco Secure Firewall Management Center (FMC)
Description
A vulnerability in the sftunnel inter-device communication protocol of Cisco Secure FMC Software could allow an authenticated, remote attacker to obtain root privileges. This vulnerability is due to unsecured deserialization of untrusted data over the sftunnel management connection. An attacker could exploit this vulnerability by sending crafted sftunnel remote procedure calls (RPCs). A successful exploit could allow the attacker to gain root privileges on a device that is running Cisco Secure FMC Software and its high-availability peer. To exploit this vulnerability, the attacker must have valid administrative credentials on a managed Cisco FTD device.
CVSS v3.1
Score 9.1critical
Affected software
Cisco
Cisco Secure Firewall Management Center (FMC)
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability arises from unsecured deserialization of untrusted data over the sftunnel management connection in Cisco Secure FMC software. An attacker with valid administrative credentials on a managed Cisco FTD device can exploit this by sending crafted sftunnel remote procedure calls (RPCs), potentially gaining root privileges on the FMC device and its high-availability peer. The vulnerability affects numerous specific versions of Cisco Secure FMC software as listed. 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.
Potential Impact
Successful exploitation allows an authenticated remote attacker with administrative credentials on a managed Cisco FTD device to obtain root privileges on the Cisco Secure FMC device and its high-availability peer. This can lead to full system compromise, including complete control over the firewall management infrastructure.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch or official fix information is provided, organizations should monitor Cisco advisories for updates. Given the requirement for valid administrative credentials, restricting and monitoring administrative access to managed Cisco FTD devices is advisable until a fix is available.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- cisco
- Date Reserved
- 2025-10-08T11:59:15.413Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6aaaf94455bf5e2cf51ba043
Added to database: 09/16/2026, 20:17:08 UTC
Last enriched: 09/16/2026, 20:31:57 UTC
Last updated: 09/17/2026, 05:01:23 UTC
Views: 7
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