CVE-2026-20131
critical-risk
Published 2026-03-04
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.
Do I need to act?
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0.79% chance of exploitation
EPSS score — low exploit probability
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CISA KEV: actively exploited in the wild
On the Known Exploited Vulnerabilities catalog — federal agencies must patch
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
10
CVSS 10.0/10
Critical
NETWORK
/ LOW complexity
Affected Products (20)
Affected Vendors
References (3)
Technical Description
https://aws.amazon.com/blogs/security/amazon-threat-intelligence-teams-identify-...
US Government Resource
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-...
71
/ 100
critical-risk
Severity
33/34 · Critical
Exploitability
10/34 · Low
Exposure
28/34 · Critical