CVE-2026-20131
CRITICAL CISA KEVCVSS v3
10
CRITICAL
EPSS Score
1.3%
exploit probability
CISA KEV
Yes
known exploited
Exploitation
—
SSVC status
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 al
CISA Known Exploited Vulnerability
- Date Added
- 3/19/2026
- Patch Due Date
- 3/22/2026
- Ransomware Use
- Known
- Required Action
- Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Technical Details
- CVSS v3 Vector
- 3.1
- Published
- 3/4/2026
- Last Modified
- 3/25/2026
Frequently Asked Questions
What is CVE-2026-20131?
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 al
Is CVE-2026-20131 actively exploited?
Yes. CVE-2026-20131 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 3/22/2026.
What is the CVSS score for CVE-2026-20131?
CVE-2026-20131 has a CVSS v3 base score of 10 (CRITICAL severity), with vector string 3.1.
Is CVE-2026-20131 affecting your environment?
Use isMalicious to check if any of your IPs or domains are associated with this vulnerability's IOCs.