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Vulnerability record · CVE-2026-20341 · published 16 September 2026

CVE-2026-20341: Deserialization of untrusted data vulnerability

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.

9.1 CVSS 3.1 Critical EPSS 0.45% · top 63.8% CWE-502 · Deserialization of untrusted data Awaiting Analysis
9.1CVSS 3.1 base score
0.45%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
1References
18 Sep 2026Last modified by NVD

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:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

References

LinkTags
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-mulivulns-4PsnFwvx

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Source: NIST National Vulnerability Database (record CVE-2026-20341), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.