CVEs / CVE-2026-20131
CVE-2026-20131: Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data Vulnerability
- Known exploited in the CISA KEV catalog since 19 Mar 2026
- critical 10 CVSS 3.1 (from the CNA)
- EPSS 44.4% chance of exploitation in the next 30 days, higher than 98% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management contain a deserialization of untrusted data vulnerability in the web-based management interface that could allow an unauthenticated, remote attacker to execute arbitrary Java code as root on an affected device.
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.
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.0.0 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.0.0.1 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.0.1 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.1.0 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 6.4.0.13 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.0.1.1 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 6.4.0.14 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.1.0.1 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.0.2 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 6.4.0.15 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.2.0 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.0.2.1 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.0.3 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.1.0.2 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.2.0.1 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.0.4 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.2.1 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.0.5 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 6.4.0.16 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.3.0 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.2.2 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.3.1 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.2.3 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.1.0.3 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.2.3.1 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.2.4 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.0.6 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.2.4.1 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.2.5 | — |
| Cisco Cisco Secure Firewall Management Center (FMC) | 7.3.1.1 | — |
Exploitation
| In CISA KEV since | 19 Mar 2026 |
|---|---|
| Due date for US federal agencies | 22 Mar 2026 |
| Used in ransomware campaigns | Known |
| Required action | Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. |
Severity
| CVSS 3.1 | 10 criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HScored by the CNA ([email protected]) |
|---|---|
| Weakness | CWE-502 |
References
- CVE-2026-20131 on NVD
- CVE-2026-20131 in the CISA KEV catalog
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-rce-NKhnULJh (cited by CISA)
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-rce-NKhnULJh Vendor Advisory
- https://aws.amazon.com/blogs/security/amazon-threat-intelligence-teams-identify-interlock-ransomware-campaign-targeting-enterprise-firewalls/ Technical Description
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20131 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.