# CVE-2026-20242: Cisco Secure Firewall Management Center Java deserialization RCE

Source: https://junglewise.ai/threats/cve-2026-20242-cisco-secure-firewall-management-center-java-deserialization-rce  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-16. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-20242 · Severity: critical · CVSS 9.8 · Published 2026-09-16

Cisco Secure Firewall Management Center is a central management platform for enterprise firewalls. A flaw in its External Database Access feature allows an attacker with network access to a database host on the allowlist to send a malicious serialized Java object, achieving remote code execution with root privileges. This can lead to complete compromise of the firewall management infrastructure.

Technologies: [Cisco Secure Firewall Management Center](https://junglewise.ai/threats/technologies/secure-firewall-management-center). Vendors: [Cisco](https://junglewise.ai/threats/vendors/cisco).

## Quick answers

**Is CVE-2026-20242 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-20242 being exploited in the wild.

**How severe is CVE-2026-20242?** Critical severity, with a CVSS score of 9.8, published 16 September 2026.

**Which products and versions are affected?** Cisco Secure Firewall Management Center multiple versions affected; see Cisco Software Checker for specific release information.

**Is there a fix for CVE-2026-20242?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-20242 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-20242?** Check whether you run Cisco Secure Firewall Management Center at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is an insecure Java deserialization flaw (CWE-502) in the External Database Access feature of Cisco Secure Firewall Management Center. An unauthenticated remote attacker who controls a host configured in the external database access list can exploit this by sending a crafted serialized Java byte stream to a specific TCP port. The vulnerability allows arbitrary command execution with root privileges. Cisco has released software updates to address this issue; no workarounds are available, though disabling External Database Access mitigates the risk until patching.

## Affected products

- Cisco Secure Firewall Management Center multiple versions affected; see Cisco Software Checker for specific release information

## Timeline

- 2026-09-16: disclosed: CVE-2026-20242 published by Cisco

## References

- [https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-javarce-y2NypXwk](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-javarce-y2NypXwk)

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