CVE-2026-111936 in Sigma File Manager
Summary
by MITRE • 10/19/2026
Sigma File Manager through 2.2.0 contains a server-side request forgery vulnerability because validate_remote_url() in security.rs never checks resolved IP addresses for extension download commands. A malicious extension or catalog entry can use hostnames resolving to loopback, private, or cloud metadata addresses to read internal responses via files written to the extension directory.
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Analysis
by VulDB Data Team • 10/19/2026
The Sigma File Manager application, specifically through version 2.2.0, contains a critical server-side request forgery vulnerability rooted in inadequate input validation within its security module. The core technical flaw resides in the validate_remote_url function located in the security.rs file, which is responsible for processing extension download commands and catalog entries. This function fails to perform necessary checks on the resolved IP addresses of hostnames provided by users or malicious actors. By allowing URLs that resolve to loopback interfaces, private internal network ranges, or cloud metadata endpoints without restriction, the application inadvertently permits requests to be directed toward resources that are typically inaccessible from external networks.
This lack of validation enables an attacker to craft a malicious extension or catalog entry containing a URL pointing to sensitive internal services. When the application processes this request, it resolves the hostname and initiates the download operation without verifying whether the destination is local or private. Consequently, the server acts as a proxy for these requests, allowing the attacker to read responses from internal APIs, configuration files, or cloud instance metadata that contain credentials and other sensitive data. The retrieved information can then be written to the extension directory on the server's file system, effectively exfiltrating confidential information through legitimate application channels.
The operational impact of this vulnerability is significant as it compromises the confidentiality of internal systems and potentially exposes critical infrastructure details. Attackers with access to the Sigma File Manager interface or those who can influence catalog entries can leverage this flaw to map internal network topologies, steal authentication tokens stored in cloud metadata services, or interact with backend microservices that are not intended for public exposure. This type of attack aligns closely with CWE-918, which describes Server-Side Request Forgery (SSRF), where a web server is tricked into making requests to unintended destinations. Furthermore, the exploitation technique corresponds to ATT&CK tactic T1557, specifically Adversary-in-the-Middle or Lateral Tool Transfer scenarios involving SSRF for internal reconnaissance and data theft.
To mitigate this vulnerability, developers must implement strict validation logic within the validate_remote_url function that goes beyond simple URL parsing. It is essential to resolve hostnames to their IP addresses before processing requests and then verify that these IPs do not fall into reserved ranges such as loopback (127.0.0.0/8), link-local, private local networks (e.g., 10.0.0.0/8, 192.168.0.0/16), or cloud metadata endpoints like 169.254.169.254. Implementing a deny-list approach for these IP ranges is insufficient due to potential IPv6 bypasses; therefore, an allow-list strategy that restricts connections to explicitly trusted domains and public IPs is recommended. Additionally, applying network-level controls such as egress filtering can prevent the server from initiating outbound connections to internal or private addresses regardless of application-layer validation failures.