CVE intelligence and bounded remediation

CVE-2026-20131 — Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrus…

Critical CVSS 10 CISA KEV

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.

Severity
Critical
CVSS
10 (3.1)
Published
2026-03-04
CISA KEV
Known exploited
Ecosystem
java/maven
Weaknesses
CWE-502

Affected products

  • cisco / secure_firewall_management_center / 6.4.0.13
  • cisco / secure_firewall_management_center / 6.4.0.14
  • cisco / secure_firewall_management_center / 6.4.0.15
  • cisco / secure_firewall_management_center / 6.4.0.16
  • cisco / secure_firewall_management_center / 6.4.0.17
  • cisco / secure_firewall_management_center / 6.4.0.18

Showing 6 representative product identities from 71 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Unsafe deserialization and object reconstruction

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Check exposure

  • Inventory serialization formats accepted from requests, queues, caches, files, cookies, and cross-service messages.
  • Trace whether untrusted input can select classes, types, callbacks, constructors, or object hooks during decoding.
  • Identify signing, schema validation, trust-boundary, and compatibility settings for each decoder.

Remediate safely

  • Replace native object deserialization with a data-only format and explicit schema validation.
  • If replacement is not immediate, use a safe decoder with a minimal type allowlist and disable polymorphic or executable hooks.
  • Update the affected library and add inert tests for unknown types, extra fields, malformed nesting, and unsigned data.

Authoritative sources

Complete CVE record and remediation plan

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