CVE-2025-20306: Cisco Secure Firewall Management Center RCE

CVE-2025-20306 Overview

Cisco disclosed a command injection vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software. The flaw stems from insufficient input validation of certain HTTP request parameters sent to the management interface. An authenticated remote attacker with Administrator-level privileges can send a crafted HTTP request to execute arbitrary commands as the root user on the underlying operating system. The vulnerability is tracked as [CWE-77] (Improper Neutralization of Special Elements used in a Command). Cisco published this issue in advisory cisco-sa-fmc-cmd-inj-HCRLpFyN.

Critical Impact
Successful exploitation grants root command execution on the FMC appliance, enabling attackers to pivot across managed firewalls, tamper with security policy, and modify or disable logging.

Affected Products

Cisco Secure Firewall Management Center Software 6.2.3 through 6.2.3.18
Cisco Secure Firewall Management Center Software 6.4.0 through 6.6.7.2, 7.0.0 through 7.4.2.2
Cisco Secure Firewall Management Center Software 7.6.0 and 7.7.0

Discovery Timeline

2025-08-14 - CVE-2025-20306 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-20306

Vulnerability Analysis

The vulnerability is a post-authentication command injection in the FMC web management interface. FMC accepts HTTP request parameters that are later incorporated into operating system command invocations without sufficient neutralization of shell metacharacters. An attacker who has already authenticated with Administrator privileges can inject arbitrary shell syntax into these parameters and have it executed by the host operating system.

Because the FMC web services run with elevated privilege on the appliance, injected commands execute as root. This gives the attacker complete control of the management plane, including the ability to read sensitive configuration data, modify managed Firepower device policies, and persist on the appliance.

Root Cause

The root cause is improper input validation of specific HTTP request parameters processed by the FMC web interface. Parameter values flow into a command construction path without escaping or allow-listing, matching the [CWE-77] command injection pattern.

Attack Vector

Exploitation requires network access to the FMC management interface and valid Administrator credentials. The attacker authenticates to the web UI, then issues a crafted HTTP request where the vulnerable parameter contains injected shell syntax. The server executes the resulting command on the underlying OS with root privileges. Prerequisite Administrator access limits remote opportunistic exploitation but is realistic in scenarios involving credential theft, insider misuse, or compromise of an administrator workstation.

No verified public proof-of-concept is available. See the Cisco Security Advisory
(cisco-sa-fmc-cmd-inj-HCRLpFyN) for vendor-provided technical details.

Detection Methods for CVE-2025-20306

Indicators of Compromise

Unexpected shell processes (for example sh, bash, /bin/sh -c) spawned as children of the FMC web server or Tomcat process on the appliance.
HTTP POST or GET requests to administrative FMC endpoints containing shell metacharacters such as ;, |, `, $( ), or && in parameter values.
New or modified files in system paths, unexpected cron entries, or new local accounts on the FMC appliance.
Outbound connections from the FMC appliance to untrusted hosts following administrator-authenticated sessions.

Detection Strategies

Audit FMC audit.log and web interface access logs for Administrator sessions that issue unusual sequences of configuration or diagnostic API calls.
Correlate administrator logins with subsequent process creation on the appliance where network telemetry is available.
Alert on any process execution lineage where the FMC web stack is the parent of a shell interpreter.

Monitoring Recommendations

Forward FMC syslog, audit, and HTTPS access logs to a centralized SIEM for retention and correlation.
Monitor privileged account activity on FMC and alert on administrator logins from new source IPs, new user agents, or outside business hours.
Track configuration changes pushed from FMC to managed devices and flag changes that were not opened as a change request.

How to Mitigate CVE-2025-20306

Immediate Actions Required

Apply the fixed FMC software release identified in Cisco advisory cisco-sa-fmc-cmd-inj-HCRLpFyN for your installed train.
Restrict access to the FMC web management interface to a dedicated management network and a small set of jump hosts.
Rotate Administrator credentials and enforce multi-factor authentication for all FMC administrative accounts.
Review recent Administrator session activity and configuration changes for signs of abuse.

Patch Information

Cisco has released fixed software addressing CVE-2025-20306. Refer to the Cisco Security Advisory for FMC Command Injection for the specific fixed release that corresponds to each affected 6.x, 7.x, 7.4, 7.6, and 7.7 train. Cisco has not published workarounds; upgrading is required.

Workarounds

No vendor-supplied workarounds are available. Reduce exposure by limiting network reachability of the FMC web interface to authorized management subnets.
Enforce least privilege: minimize the number of accounts granted the Administrator role and prefer scoped roles for routine operations.
Require MFA and session logging for every account that retains Administrator access until patching is complete.

bash

# Example network restriction concept (adapt to your environment)
# Permit only the management jump host subnet to reach FMC HTTPS
access-list FMC_MGMT permit tcp 10.10.0.0 255.255.255.0 host <FMC_IP> eq 443
access-list FMC_MGMT deny   tcp any host <FMC_IP> eq 443