Secure Firewall Management CenterApplication · Cisco
CVE-2026-20131
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThis is an insecure deserialization vulnerability in the web-based management interface of Cisco Secure FMC. An unauthenticated remote attacker can send a crafted serialized Java object to the management interface, which gets deserialized without proper validation, allowing arbitrary Java code execution with root privileges.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Secure Firewall Management CenterApplication
= 6.4.0.13= 6.4.0.14= 6.4.0.15= 6.4.0.16= 6.4.0.17= 6.4.0.18= 7.0.0= 7.0.0.1= 7.0.1= 7.0.1.1= 7.0.2= 7.0.2.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Cisco FMC installationConfirm the presence of Cisco Secure Firewall Management Center in your environment by checking system inventory or using CLI command 'show version' on the deviceAffected if FMC Software is installed and running
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Check FMC software versionRun the CLI command 'show version' or access the FMC web interface and navigate to Help > About to display the installed version numberAffected if Version matches any of: 6.4.0.13, 6.4.0.14, 6.4.0.15, 6.4.0.16, 6.4.0.17, 6.4.0.18, 7.0.0, 7.0.0.1, 7.0.1, 7.0.1.1, 7.0.2, 7.0.2.1
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Verify web interface accessibilityConfirm the FMC web-based management interface is enabled and accessible by attempting to reach the management IP on ports 443 or 8443 from your local networkAffected if The web management interface is reachable over the network
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Assess network exposureReview firewall rules, NAT configurations, and ACLs to determine if the FMC management interface IP is exposed to untrusted or external networksAffected if The FMC web interface is reachable from untrusted networks or the public internet
You are affected if Cisco FMC Software is installed with a version matching the affected list AND the web-based management interface is network-accessible, particularly from untrusted networks.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedRestrict network access to the FMC management interface to prevent unauthenticated external access (do not expose to public internet), and apply Cisco's available security patches for this vulnerability.
Contact Cisco for the specific fixed version (typically a later 6.4.0.x or 6.5.x/6.6.x release beyond 6.4.0.16)
- 1. Contact Cisco Technical Support or visit the Cisco Security Advisory page to obtain the exact fixed version for this vulnerability.
- 2. Download the recommended fixed version of Cisco Secure Firewall Management Center Software.
- 3. Review the upgrade guide for FMC at https://www.cisco.com/c/en/us/td/docs/security/firepower/upgrade_guide/fpmc_upgrade_guide.html
- 4. Schedule a maintenance window and create a full backup of the FMC configuration.
- 5. Perform the upgrade to the fixed version following Cisco's documented upgrade procedure.
- 6. After upgrade, verify the FMC version matches the fixed release and confirm normal functionality.
- 7. If the FMC management interface was exposed to the internet, ensure it is behind a VPN, ACL, or not directly accessible from untrusted networks.
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Secure Firewall Management Center
Exploited in the wild — priority engagement
- Consultation6.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,968.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-20131 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-20131 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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