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.
Analysis
Analysis and contextual insights are available on OpenCVE Cloud.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Cisco | Cisco Secure Firewall Management Center (FMC) | unknown |
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No data available yet.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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Wed, 16 Sep 2026 20:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Cisco Secure Firewall Management Center Software Java Deserialization Remote Code Execution Vulnerability | |
| Weaknesses | CWE-502 | |
| References |
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| Metrics |
cvssV3_1
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Subscriptions
No data.
MITRE
Status: PUBLISHED
Assigner: cisco
Published:
Updated: 2026-09-16T20:08:27.904Z
Reserved: 2025-10-08T11:59:15.400Z
Link: CVE-2026-20242
Vulnrichment
No data.
NVD
Status : Awaiting Analysis
Published: 2026-09-16T20:17:22.697
Modified: 2026-09-16T20:35:23.620
Link: CVE-2026-20242
Redhat
No data.
OpenCVE Enrichment
No data.
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CWE-502
Deserialization of Untrusted Data