CVE-2026-76420 Cisco Secure Firewall Management Center Software Impersonated sftunnel Connection Vulnerability
An unauthenticated remote attacker can impersonate a peer device to execute commands as root and control FMC APIs if the sftunnel connection is down.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-76420?
CVE-2026-76420 is a critical authentication bypass vulnerability in Cisco Secure Firewall Management Center (FMC), published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-285
Which versions are affected by CVE-2026-76420?
How do I fix CVE-2026-76420?
No fix has been published for CVE-2026-76420 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-76420 being exploited?
There is no known exploitation of CVE-2026-76420 in the wild and no public exploit code.
Sources
Also known as GHSA-4fw2-5j8h-69f2.