CVE-2026-20131

A vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated…

Browse: All 2026 CVEs · All vendors

CVSS score
10.0 Critical
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CISA KEV
Yes — actively exploited (added 2026-03-19, remediation due 2026-03-22)
Ransomware
Known ransomware campaign use
Weakness (CWE)
CWE-502
Published
2026-03-04
Last modified
2026-06-17
NVD status
Analyzed

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.

Affected products

Affected ranges per NVD CPE data; confirm exact versions in the vendor advisory.

Required action (CISA)

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Federal remediation deadline: 2026-03-22.

How to prioritize this

This vulnerability is on the CISA KEV list, meaning it is being actively exploited — treat it as urgent regardless of the raw CVSS number. Use the live CVE lookup for the latest NVD data, and the CVSS 3.1 calculator to model your own environmental score.

References

FAQ

Is CVE-2026-20131 actively exploited?

Yes. CISA added CVE-2026-20131 to its Known Exploited Vulnerabilities (KEV) catalog on 2026-03-19, with a federal remediation deadline of 2026-03-22. A KEV listing means real-world exploitation is confirmed, so patching this should be prioritized above many higher-CVSS bugs that aren't being exploited.

What is the CVSS score of CVE-2026-20131?

CVE-2026-20131 has a CVSS base score of 10.0 (Critical). Its vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

Related vulnerabilities

Data source: NVD & CISA KEV. Shown as-is; nothing added. Last generated from NVD data — re-check the live tool for updates.