CVE-2026-20324
CRITICAL 9.9 ALL-YEARSA vulnerability in the sftunnel inter-device communication protocol of Cisco Secure Firewall Management Center (FMC) Software could allow an authenticated, remote attacker to execute arbitrary commands as root. This vulnerability exists because a registered sftunnel peer has incorrect permissions to write an arbitrary file to any location on the device. An attacker could exploit this vulnerability by hijacking the sftunnel communication connection or being a valid registered sftunnel peer and sending an sftunnel command to write a malicious file to the disk of an affected device. A successful exploit could allow the attacker to write a file to the device that is executed with root privileges. To exploit this vulnerability, the attacker must have valid user credentials on the affected device.
Severe if exploited (CVSS 9.9), but no confirmed exploitation. Patch on a normal cadence.
Exploitation likelihood
0.4%chance of exploitation in 30 days · 38th percentile
Impact if exploited
9.9CVSS 3.1 · CRITICAL · CNA
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityHigh
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ⚠Privileges: Requires a low-privilege account
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept & exploit code
No public exploit or proof-of-concept code is catalogued for this CVE (no ExploitDB, Nuclei, or CISA-KEV entry). It may still exist — search GitHub or check the references below.
Weakness (CWE)
- CWE-862: Missing Authorization
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
All CVSS metrics
- CRITICAL 9.9 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - CRITICAL 9.9 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H