CVE-2026-20242

CRITICAL

A vulnerability in the External Database Access feature of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated, remote attacker to execute arbitrary commands as&nb...

Affects 1 product across 1 vendor.

CVSS 3.19.8
EPSS0.6%
Percentile49th
PatchUnknown
CVSS Vector — Plain English Remotely exploitable over the network, low complexity, no authentication required, no user interaction needed, impact contained to the vulnerable component, full confidentiality impact, full integrity impact, full availability impact.
CWE Weakness Definitions
CWE-502: Deserialization of Untrusted Data

Software deserializes untrusted data without validation, allowing crafted objects to execute arbitrary code.

Related Attack Patterns (CAPEC)
CAPEC-586 Object Injection
via CWE-502

Mapping is CWE-to-CAPEC per MITRE CAPEC 3.9.

◆ AI Analysis — automated analysis, not human-reviewed

A high severity vulnerability (CVE-2026-20242) affects the target system. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Cisco Secure Firewall Management Center. Authentication is not required to exploit this vulnerability. The ZDI has assigned a CVSS rating of 8.1. The fo...

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Frequently Asked Questions
What is CVE-2026-20242?
A high severity vulnerability (CVE-2026-20242) affects the target system. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Cisco Secure Firewall Management Center. Authentication is not required to exploit this vulnerability. The ZDI has assigned a CVSS rating of 8.1. The fo...
What is the CVSS score for CVE-2026-20242?
CVE-2026-20242 has CVSS 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS: 0.6%.
Is CVE-2026-20242 actively exploited?
No confirmed active exploitation of CVE-2026-20242 as of 2026-09-25.
How do I remediate CVE-2026-20242?
Apply vendor patches for CVE-2026-20242. Monitor Cisco advisories.
What systems are affected by CVE-2026-20242?
CVE-2026-20242 affects: Cisco.
Vulnerability Details
CVE IDCVE-2026-20242
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published2026-09-16
Last Modified2026-09-18
ICS Relevance80%
Weakness (CWE)
Deserialization of Untrusted Data
SourceNVD
Official Description

A vulnerability in the External Database Access feature of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated, remote attacker to execute arbitrary commands as root on an affected device. This vulnerability is due to insecure deserialization of a user-supplied Java byte stream from a host that is configured in the external database access list. An attacker could exploit this vulnerability by sending a crafted, serialized Java byte stream to a specific TCP port of an affected device. A successful exploit could allow the attacker to execute arbitrary commands on the device and elevate privileges to root. Notes: This vulnerability can be exploited only by an attacker who has control of a host in the external database access list. If the FMC management interface does not have public internet access, the attack surface that is associated with this vulnerability is reduced.

Source: NIST NVD / MITRE CVE Database

Affected Products
VendorProductFixed Version
Cisco Cisco Secure Firewall Management Center —
Remediation

No patch URL on record. Monitor vendor security advisories directly.

Threat Intelligence
● Threat Intelligence Validated: September 2026 | Threat Age: 11 Days
CISA KEVNot in KEV catalog
Public ExploitNot confirmed
PoC CodeNot confirmed
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