CVE-2026-20342 in Secure Firewall Management Center
Summary
by MITRE • 09/16/2026
A vulnerability in a specific file download API of Cisco Secure FMC Software could allow an authenticated, remote attacker to download arbitrary files from an affected system.
This vulnerability exists because user input is not being sanitized. An attacker could exploit this vulnerability by sending a crafted HTTPS request. A successful exploit could allow the attacker to download arbitrary files from the affected system. To exploit this vulnerability, the attacker must have valid credentials for a user account with at least the role of Security Analyst (read-only).
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Analysis
by VulDB Data Team • 09/16/2026
The identified security flaw resides within the file download application programming interface of Cisco Secure Firepower Management Center software, presenting a significant risk to systems relying on centralized network management and policy enforcement. This vulnerability is classified as an insecure direct object reference or path traversal issue, stemming from insufficient validation of user-supplied input during file retrieval operations. The core technical deficiency lies in the failure to sanitize filenames or paths provided by the client application before processing them against the server's filesystem structure. When a request is received, the system does not adequately verify that the requested resource exists within an allowed directory scope or that the filename contains only safe characters. This lack of input sanitization allows for the manipulation of file path parameters to reference files outside the intended context, effectively bypassing access controls designed to restrict users to specific data sets.
From a technical perspective, this flaw enables what is commonly known as arbitrary file read functionality. An authenticated attacker can construct a malicious HTTPS request containing specially crafted parameters that traverse directory boundaries using sequences such as dot-dot-slash or encoded variations thereof. By exploiting this mechanism, the adversary gains the ability to access sensitive configuration files, credential stores, database dumps, and other critical system artifacts stored on the management server. The operational impact of successful exploitation is severe, as it compromises the confidentiality integrity of the entire managed environment. Since Firepower Management Center serves as the central point for policy distribution and monitoring across a network infrastructure, accessing its underlying file system can reveal sensitive information about network topology, security policies, authentication mechanisms, and potentially credentials used to manage connected devices. This access could serve as an initial foothold for further lateral movement or privilege escalation within the organization's IT ecosystem.
The exploitation of this vulnerability requires specific preconditions that limit its immediate threat landscape but do not eliminate it entirely. The attacker must possess valid credentials for a user account with at least the Security Analyst role, which is typically assigned to personnel responsible for monitoring network traffic and viewing alerts rather than configuring system settings. While this requirement restricts access to insiders or attackers who have compromised lower-privileged accounts, it remains a realistic attack vector given that analyst-level permissions are often granted broadly within security operations centers. The attacker interacts with the service by sending crafted HTTPS requests, leveraging standard web protocols which may bypass some network-based intrusion detection systems if not properly monitored for anomalous file access patterns.
To mitigate this risk and align with industry best practices such as those outlined in the Common Weakness Enumeration (CWE) under CWE-22 Improper Limitation of a Pathname to a Restricted Directory, organizations should ensure that their Cisco Secure FMC software is updated to versions where input validation has been strengthened. Implementing strict allow-lists for file names and enforcing canonicalization checks before filesystem access are critical technical controls. Additionally, defense-in-depth strategies recommend restricting the permissions of Security Analyst accounts wherever possible, adhering to the principle of least privilege by granting only necessary read-only access without excessive system-level privileges. Network segmentation should also be employed to isolate management interfaces from general user networks, reducing the attack surface available to potential adversaries who may have obtained valid credentials through phishing or other credential theft techniques. Continuous monitoring for unusual file download activities and implementing robust logging mechanisms can further aid in detecting exploitation attempts before significant data exfiltration occurs.