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CVE-2026-20131

CRITICAL KEV CISA Exploitation: ACTIVE Ransomware noto
10.0
CVSS 3.1
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.

Metadata

CVE ID
CVE-2026-20131
State
PUBLISHED
Assigner
cisco
Reserved
2025-10-08 11:59 UTC
Published
2026-03-04 17:17 UTC
Last updated
2026-03-25 16:04 UTC
Primary CWE
CWE-502
Deserialization of Untrusted Data
Vendor / Product
Cisco / Cisco Secure Firewall Management Center (FMC)
Sources
cve.org  ·  NVD

Severity & Metrics

10.0 CRITICAL CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
SSVC — CISA Coordinator
Exploitation
ACTIVE
Automatable
yes
Tech. Impact
total
CISA Known Exploited Vulnerability
Vulnerability name
Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data Vulnerability
Vendor
Cisco
Product
Secure Firewall Management Center (FMC)
Added to KEV
2026-03-19
Due date
2026-03-22
Ransomware
Known use
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.
CISA description
Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management contain a deserialization of untrusted data vulnerability in the web-based management interface that could allow an unauthenticated, remote attacker to execute arbitrary Java code as root on an affected device.
Affected products (1)
VendorProductPlatformVersions
Cisco Cisco Secure Firewall Management Center (FMC) — 7.0.0, 7.0.0.1, 7.0.1, 7.1.0 …
Weakness (CWE)
CWESourceDescription
CWE-502 cna Deserialization of Untrusted Data
CVSS scores (1)
ScoreSeverityVersionSourceVector
10.0 CRITICAL 3.1 cna CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
References (1)
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