CVE-2026-100391 in MediaFlow Proxy
Summary
by MITRE • 09/25/2026
MediaFlow Proxy through 2.4.9 contains a server-side request forgery vulnerability in the /proxy routes due to missing and incomplete destination validation in the d query parameter. Remote attackers can supply arbitrary internal URLs including loopback and cloud metadata endpoints to read full responses from the proxy server.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/25/2026
The MediaFlow Proxy software, specifically through version 2.4.9, suffers from a critical Server-Side Request Forgery vulnerability within its /proxy endpoint handling logic. This flaw stems directly from insufficient validation of user-supplied input in the d query parameter, which is intended to specify the destination URL for proxied requests. The application fails to adequately restrict or sanitize this parameter, allowing remote attackers to inject arbitrary Uniform Resource Locators that point not only to external malicious sites but also to internal network resources and local loopback addresses. This lack of rigorous input validation creates a direct pathway for exploitation by any unauthenticated user who can interact with the proxy service over the network.
From a technical perspective, the vulnerability exploits the trust relationship between the application server and its underlying infrastructure. By manipulating the d parameter, an attacker instructs the MediaFlow Proxy to fetch content from internal endpoints that are typically inaccessible from outside the local network or cloud environment. This includes sensitive resources such as localhost services running on ports not exposed publicly, as well as cloud provider metadata endpoints like those found in AWS EC2 instances (e.g., 169.254.169.254) or Azure managed identities. The proxy server acts as a blind relay, fetching the response from these internal targets and returning it to the attacker without filtering or inspecting the content for sensitive data patterns such as authentication tokens, private keys, or configuration secrets stored in metadata services.
The operational impact of this vulnerability is severe, primarily facilitating unauthorized access to internal network resources and potential credential theft. Attackers can leverage this flaw to perform port scanning against internal hosts by observing response times or error messages, effectively mapping the internal network topology from a remote position. More critically, accessing cloud instance metadata endpoints allows attackers to retrieve temporary security credentials assigned to running instances. These credentials often grant access to other services within the same cloud project or account, leading to a complete compromise of the affected infrastructure. In on-premises deployments, this could lead to unauthorized access to internal administrative interfaces, database servers, or other critical backend systems that rely on network segmentation for security.
This vulnerability aligns with CWE-918, which describes Server-Side Request Forgery (SSRF), specifically falling under the sub-category of fetching metadata from cloud providers due to insufficient validation of user-controlled URLs. In terms of offensive cyber operations, this technique corresponds to ATT&CK tactic T1557, Adversary-in-the-Middle, where an attacker uses a compromised or vulnerable system as a proxy to move laterally within a network and access resources that would otherwise be protected by firewalls or security groups. The ability to read full responses from the proxy server means that any data returned by internal services is exfiltrated directly to the attacker, bypassing traditional perimeter defenses designed to block external-to-internal traffic while allowing internal-to-external outbound connections.
Mitigation strategies must focus on implementing strict allow-lists for destination URLs rather than relying solely on deny lists or simple pattern matching which can often be evaded through encoding techniques or protocol variations. Developers should enforce that the d parameter only accepts specific, trusted domains and IP ranges relevant to the application's legitimate functionality. It is crucial to disable HTTP redirects within the proxy logic to prevent attackers from chaining requests to bypass initial validation checks. Additionally, implementing network-level controls such as egress filtering can limit the ability of the server to connect to internal metadata endpoints or unauthorized external hosts. For organizations currently running versions up to 2.4.9, upgrading to a patched version that includes these rigorous input validations is the primary remediation step, supplemented by immediate review of access logs for signs of exploitation attempts involving loopback addresses or cloud metadata IP ranges.