CVE-2026-20131
Cisco Secure Firewall Management Center Software Remote Code Execution Vulnerability
- Published
- Mar 4, 2026
- Updated
- Aug 14, 2026
- Assigning CNA
- cisco
- Evidence observed
- Mar 19, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HModerate · next 30 days
- Percentile
- 98.3%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
CISA Known Exploited
This CVE appears in the CISA Known Exploited Vulnerabilities catalog.
Summary
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.
Sources
5- CVE-2026-20131Exploit
CVE-2026-20131
- CVE-2026-20131-Post-Incident-Written-ReportInformational
Post-incident report on CVE-2026-20131 (CVSS 10.0), a Cisco FMC insecure deserialization vulnerability exploited by Interlock ransomware. Details root-cause analysis, lateral movement tactics, and emergency containment strategies.
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