CVE-2026-20131 Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data
Unauthenticated remote attackers can execute arbitrary Java code as root via insecure deserialization in the Cisco Secure Firewall Management Center web interface.
- Exploited in the wild
- Since 19 Mar 2026
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-20131?
CVE-2026-20131 is a critical unsafe deserialization vulnerability in Cisco Secure Firewall Management Center, published on 4 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated, remote attacker to execute arbitrary Java code as root on an affected device. This vulnerability is due to insecure deserialization of a user-supplied Java byte stream. An attacker could exploit this vulnerability by sending a crafted serialized Java object to the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary code on the device and elevate privileges to root. Note: If the FMC management interface does not have public internet access, the attack surface that is associated with this vulnerability is reduced.
Weakness: CWE-502
Which versions are affected by CVE-2026-20131?
It affects 1 product.
Products include Cisco Secure Firewall Management Center.
How do I fix CVE-2026-20131?
No fix has been published for CVE-2026-20131 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 22 Mar 2026.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-20131 being exploited?
Yes. Attackers have exploited CVE-2026-20131 in the wild since at least 19 Mar 2026, including in ransomware campaigns.
Public exploit code: 6 proofs of concept on GitHub.
Other vulnerabilities in Cisco Secure Firewall Management Center
- CVE-2026-20079 Cisco Firewall Management Center Authentication Bypass Using an Alternate Path or Channel
- CVE-2026-20316 Cisco Secure Firewall Management Center Use of Hard-coded Password
- CVE-2025-20265 Cisco Secure Firewall Management Center Software Radius Remote Code Execution Vulnerability
- CVE-2024-20424 Command injection in Cisco Firepower Management Center
- CVE-2023-20048 Missing authorization in Cisco Firepower Management Center
Sources
Also known as GHSA-r229-mj76-g2qx.