CVE-2026-20131
Last modified
CVE-2026-20131 is a critical-severity vulnerability rated 10/10 on the CVSS scale. A 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. CISA has confirmed active exploitation in the wild. EPSS estimates a 27.55% chance of exploitation in the next 30 days.
Description
A 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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Exploitation Status
This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by .
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Cisco | Secure Firewall Management Center | 6.4.0.13 |
| Cisco | Secure Firewall Management Center | 6.4.0.14 |
| Cisco | Secure Firewall Management Center | 6.4.0.15 |
| Cisco | Secure Firewall Management Center | 6.4.0.16 |
| Cisco | Secure Firewall Management Center | 6.4.0.17 |
| Cisco | Secure Firewall Management Center | 6.4.0.18 |
| Cisco | Secure Firewall Management Center | 7.0.0 |
| Cisco | Secure Firewall Management Center | 7.0.0.1 |
| Cisco | Secure Firewall Management Center | 7.0.1 |
| Cisco | Secure Firewall Management Center | 7.0.1.1 |
| Cisco | Secure Firewall Management Center | 7.0.2 |
| Cisco | Secure Firewall Management Center | 7.0.2.1 |
| Cisco | Secure Firewall Management Center | 7.0.3 |
| Cisco | Secure Firewall Management Center | 7.0.4 |
| Cisco | Secure Firewall Management Center | 7.0.5 |
| Cisco | Secure Firewall Management Center | 7.0.6 |
| Cisco | Secure Firewall Management Center | 7.0.6.1 |
| Cisco | Secure Firewall Management Center | 7.0.6.2 |
| Cisco | Secure Firewall Management Center | 7.0.6.3 |
| Cisco | Secure Firewall Management Center | 7.0.7 |
| Cisco | Secure Firewall Management Center | 7.0.8 |
| Cisco | Secure Firewall Management Center | 7.0.8.1 |
| Cisco | Secure Firewall Management Center | 7.1.0 |
| Cisco | Secure Firewall Management Center | 7.1.0.1 |
| Cisco | Secure Firewall Management Center | 7.1.0.2 |
| Cisco | Secure Firewall Management Center | 7.1.0.3 |
| Cisco | Secure Firewall Management Center | 7.2.0 |
| Cisco | Secure Firewall Management Center | 7.2.0.1 |
| Cisco | Secure Firewall Management Center | 7.2.1 |
| Cisco | Secure Firewall Management Center | 7.2.2 |
| Cisco | Secure Firewall Management Center | 7.2.3 |
| Cisco | Secure Firewall Management Center | 7.2.3.1 |
| Cisco | Secure Firewall Management Center | 7.2.4 |
| Cisco | Secure Firewall Management Center | 7.2.4.1 |
| Cisco | Secure Firewall Management Center | 7.2.5 |
| Cisco | Secure Firewall Management Center | 7.2.5.1 |
| Cisco | Secure Firewall Management Center | 7.2.5.2 |
| Cisco | Secure Firewall Management Center | 7.2.6 |
| Cisco | Secure Firewall Management Center | 7.2.7 |
| Cisco | Secure Firewall Management Center | 7.2.8 |
| Cisco | Secure Firewall Management Center | 7.2.8.1 |
| Cisco | Secure Firewall Management Center | 7.2.9 |
| Cisco | Secure Firewall Management Center | 7.2.10 |
| Cisco | Secure Firewall Management Center | 7.2.10.1 |
| Cisco | Secure Firewall Management Center | 7.2.10.2 |
| Cisco | Secure Firewall Management Center | 7.3.0 |
| Cisco | Secure Firewall Management Center | 7.3.1 |
| Cisco | Secure Firewall Management Center | 7.3.1.1 |
| Cisco | Secure Firewall Management Center | 7.3.1.2 |
| Cisco | Secure Firewall Management Center | 7.4.0 |
Showing 50 of 71 affected configurations. See NVD for the full list.
References
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20131US Government Resource
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
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