Cisco Secure Firewall Management Center (FMC)
Cisco Secure Firewall Management Center (FMC) is affected by a medium-severity vulnerability (CVE-2026-20316) that is confirmed to be actively exploited in the wild. Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
What is this vulnerability?
A vulnerability in the web interface of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated, remote attacker to log in to an affected device using a low-privileged account to access sensitive data within the impacted systems. This vulnerability is due to the presence of static user credentials for a low-privileged account. An attacker could exploit this vulnerability by using the account to log in to an affected system. A successful exploit could allow the attacker to log in to the affected system and access sensitive data as the low-privileged user. Note: If the FMC management interface does not have public internet access, the attack surface that is associated with this vulnerability is reduced. Cisco has assigned this security advisory a Security Impact Rating (SIR) of High rather than Medium as the score indicates. The reason is that this vulnerability can be used with other Cisco Secure FMC Software vulnerabilities to elevate privileges.
How it works
This is classified as CWE-259. In plain terms, an attacker could use this flaw in Secure Firewall Management Center (FMC) to gain access, disrupt service, or steal data — the exact impact depends on how it’s deployed in your environment.
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Mitigations
- Apply the vendor’s security patch or update as soon as it’s available and tested.
- If no patch exists yet, apply the vendor’s temporary workaround.
- Limit network exposure of the affected system until it’s patched.
- Review logs for signs of prior exploitation, especially if it’s flagged for ransomware use.
Recommendations
- Confirm whether Cisco Secure Firewall Management Center (FMC) is used anywhere in your environment.
- Patch internet-facing systems first, then internal ones.
- Set a reminder ahead of the remediation deadline so it doesn’t slip.
- Subscribe to the vendor’s security advisories for earlier warning next time.
Compiled from public threat intelligence (CISA Known Exploited Vulnerabilities catalog and the National Vulnerability Database, referenced in 1 public advisories).