CVE-2026-93569 in AMQ Broker
Summary
by MITRE • 09/18/2026
HTTP/1 absolute-form Host mismatch is translated to HTTP/2 :authority, overriding the request-target authority
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Analysis
by VulDB Data Team • 09/18/2026
The vulnerability described involves a protocol translation error within an intermediary component or proxy that converts HTTP/1.1 requests into HTTP/2 format. In standard HTTP/1.1 operations using tunneling methods such as CONNECT for HTTPS traffic, clients typically send absolute-form URIs where the full URI including the scheme and host is specified in the request line. The Host header field serves to identify the target resource when relative paths are used or when virtual hosting requires explicit domain identification. However, during the translation process from HTTP/1.1 to HTTP/2, certain implementations incorrectly map the absolute-form authority component directly into the HTTP/2 :authority pseudo-header while simultaneously allowing other parts of the request-target to override this value. This misalignment creates a discrepancy between the intended destination identified by the client and the actual target processed by the backend server or upstream service.
This technical flaw stems from improper parsing logic within the protocol translation layer, specifically failing to prioritize the :authority header correctly when an absolute URI is present in the HTTP/1.1 request line. According to RFC 9113, which defines HTTP/2 framing and semantics, the :authority pseudo-header must accurately reflect the target authority of the request. When a proxy receives an HTTP/1.1 request with an absolute-form URI like https://example.com/path, it should extract example.com as the authoritative host for translation into the :authority field. If the implementation instead allows subsequent headers or internal routing logic to override this value based on other parts of the original request-target, it introduces a state inconsistency that can be exploited by malicious actors. This behavior violates the principle of least privilege and proper input validation expected in secure proxy implementations.
The operational impact of this vulnerability is significant for organizations relying on reverse proxies, load balancers, or API gateways to manage traffic between clients and backend services. An attacker could potentially manipulate request routing by crafting specific HTTP/1.1 requests that exploit the translation mismatch. By sending a request with an absolute-form URI where the host differs from what would normally be derived via standard Host header processing, an adversary might force the proxy to route sensitive internal resources or administrative interfaces to unintended destinations. This can lead to unauthorized access to backend systems, bypassing of authentication mechanisms tied to specific domains, and potential exposure of confidential data residing on servers that should not have been accessible from external networks.
From a classification perspective, this issue aligns with CWE-20 Improper Input Validation as the core failure lies in the incorrect handling of input parameters during protocol conversion. It also relates closely to CWE-697 Incorrect Comparison since the system fails to correctly compare and prioritize authority identifiers across different parts of the request structure. In terms of attack vectors, this vulnerability supports MITM-style attacks or direct exploitation via crafted requests categorized under ATT&CK technique T1059 Command and Scripting Interpreter if it leads to remote code execution through backend services, though more commonly it falls under T1486 Data Encrypted for Impact in scenarios involving ransomware deployment on misrouted systems. It may also facilitate lateral movement within a network by allowing access to internal endpoints that were previously isolated from external traffic flows.
Mitigation strategies must focus on rigorous validation of protocol translation logic and strict adherence to RFC standards during HTTP/1.1 to HTTP/2 conversion processes. Developers should ensure that the :authority header is derived exclusively from the absolute-form URI host component when present, without allowing overrides from other request fields unless explicitly authorized by security policies. Implementing comprehensive input sanitization routines that reject malformed or ambiguous requests can prevent exploitation attempts. Additionally, deploying Web Application Firewalls with rules specifically designed to detect anomalous HTTP/2 :authority mismatches provides an additional layer of defense. Regular penetration testing and code reviews focusing on protocol handling modules are essential to identify similar translation flaws before they reach production environments. Keeping proxy software updated ensures that known issues related to RFC compliance are addressed through vendor patches, reducing the attack surface associated with these complex interoperability scenarios.