CVE-2026-20242 is a vulnerability in Cisco Secure Firewall Management Center
Published on September 16, 2026
Cisco Secure Firewall Management Center Software Java Deserialization Remote Code Execution Vulnerability
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.
Vulnerability Analysis
CVE-2026-20242 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.
Weakness Type
What is a Marshaling, Unmarshaling Vulnerability?
The application deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
CVE-2026-20242 has been classified to as a Marshaling, Unmarshaling vulnerability or weakness.
Products Associated with CVE-2026-20242
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Affected Versions
Cisco Secure Firewall Management Center (FMC):- Version 7.0.0 is affected.
- Version 7.0.0.1 is affected.
- Version 7.0.1 is affected.
- Version 7.0.1.1 is affected.
- Version 7.0.2 is affected.
- Version 7.2.0 is affected.
- Version 7.0.2.1 is affected.
- Version 7.0.3 is affected.
- Version 7.2.0.1 is affected.
- Version 7.0.4 is affected.
- Version 7.2.1 is affected.
- Version 7.0.5 is affected.
- Version 7.3.0 is affected.
- Version 7.2.2 is affected.
- Version 7.3.1 is affected.
- Version 7.2.3 is affected.
- Version 7.2.3.1 is affected.
- Version 7.2.4 is affected.
- Version 7.0.6 is affected.
- Version 7.2.4.1 is affected.
- Version 7.2.5 is affected.
- Version 7.3.1.1 is affected.
- Version 7.4.0 is affected.
- Version 7.0.6.1 is affected.
- Version 7.2.5.1 is affected.
- Version 7.4.1 is affected.
- Version 7.2.6 is affected.
- Version 7.4.1.1 is affected.
- Version 7.0.6.2 is affected.
- Version 7.2.7 is affected.
- Version 7.2.5.2 is affected.
- Version 7.3.1.2 is affected.
- Version 7.2.8 is affected.
- Version 7.6.0 is affected.
- Version 7.4.2 is affected.
- Version 7.2.8.1 is affected.
- Version 7.0.6.3 is affected.
- Version 7.4.2.1 is affected.
- Version 7.2.9 is affected.
- Version 7.0.7 is affected.
- Version 7.7.0 is affected.
- Version 7.4.2.2 is affected.
- Version 7.2.10 is affected.
- Version 7.6.1 is affected.
- Version 7.4.2.3 is affected.
- Version 7.0.8 is affected.
- Version 7.6.2 is affected.
- Version 7.7.10 is affected.
- Version 7.2.10.1 is affected.
- Version 7.0.8.1 is affected.
- Version 7.6.2.1 is affected.
- Version 7.2.10.2 is affected.
- Version 7.7.10.1 is affected.
- Version 7.4.2.4 is affected.
- Version 7.4.3 is affected.
- Version 7.6.3 is affected.
- Version 7.7.11 is affected.
- Version 7.6.4 is affected.
- Version 10.0.0 is affected.
- Version 7.4.4 is affected.
- Version 7.4.5 is affected.
- Version 7.0.9 is affected.
- Version 7.2.11 is affected.
- Version 7.7.12 is affected.
- Version 7.6.5 is affected.
- Version 7.4.6 is affected.
- Version 10.0.1 is affected.
- Version 7.4.7 is affected.