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Cisco

CVE-2026-20131

actively exploited
malware scan detection

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.

10.0
cvss critical
common vulnerability scoring system v3.1. measures intrinsic severity on a 0-10 scale.
epss 0.0060
exploitation prediction scoring system. probability this vulnerability will be exploited in the wild in the next 30 days.
kev yes
cisa known exploited vulnerabilities catalog. confirmed active exploitation.
CVSS 3.1 Common Vulnerability Scoring System v3.1
10.0 / 10
CRITICAL
exploitability
Attack Vector
Network
Attack Vector (AV:N): exploitable remotely over the network — most dangerous. no physical or adjacent access needed.
Attack Complexity
Low
Attack Complexity (AC:L): no special conditions needed. attack can be reliably reproduced.
Privileges Required
None
Privileges Required (PR:N): no authentication needed. any anonymous attacker can exploit this.
User Interaction
None
User Interaction (UI:N): no victim action needed. fully exploitable without user interaction.
impact
Scope
Changed
Scope (S:C): exploitation impacts resources beyond the vulnerable component.
Confidentiality
High
Confidentiality (C:H): total information disclosure. attacker gains access to all data within the component.
Integrity
High
Integrity (I:H): complete data modification possible. attacker can modify any data.
Availability
High
Availability (A:H): total denial of service. attacker can fully shut down the resource.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
exploit detect attrib advisory media timeline
exploitation detection attribution advisories media timeline
activity density
rdintel assessment
actively exploited. patch immediately.
ransomware in use.
flagged malicious repos detected. do not execute.
detection rules available.
75 threat composite score from 15+ signals including exploitation status, epss probability, detection coverage, and community attention. 0-100 scale.

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