CVE-2026-93003 in ThreadX
Summary
by MITRE • 10/20/2026
The Web add-on's HTTP server searches the entire request packet for header fields instead of stopping at the end of the header section. A header field name placed in the request body is therefore reported to the server as though it were a header, which lets a client control request framing decisions it should not be able to reach.
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Analysis
by VulDB Data Team • 10/20/2026
The vulnerability described constitutes a critical flaw in how the web add-on processes HTTP requests, specifically within its internal HTTP server implementation. This issue stems from an incorrect parsing logic that fails to adhere to standard HTTP protocol specifications regarding message structure. In compliant HTTP implementations, there is a distinct boundary between the header section and the body of a request, typically marked by a specific delimiter sequence such as double carriage return followed by line feed. The flaw arises because the server's parser does not terminate its search for header fields upon encountering this end-of-header marker. Instead, it continues to scan the entire incoming packet, including the payload data that constitutes the request body. This behavior fundamentally breaks the separation of concerns between metadata and content within an HTTP transaction.
From a technical perspective, this parsing error allows an attacker to inject what appears to be valid header fields into the body of a POST or PUT request. Because the server interprets these injected strings as legitimate headers, it may apply them to the processing logic intended for actual protocol-level directives. This misinterpretation can lead to severe operational impacts, including but not limited to response splitting attacks where an attacker injects newlines and header fields into user-controlled input that is later reflected in HTTP responses. It also opens the door to request smuggling scenarios, particularly if this add-on interacts with upstream proxies or load balancers that have different parsing rules for headers versus bodies. By controlling framing decisions through body-injected headers, a malicious client can manipulate how subsequent requests are interpreted by downstream components, potentially bypassing security controls like firewalls or access control lists that rely on accurate header inspection.
This vulnerability aligns with CWE-77: Improper Neutralization of Special Elements used in a Command, as it involves the injection of special characters and structures into an interpreter context where they should not be present. Furthermore, it relates to CWE-20: Improper Input Validation because the system fails to correctly validate the structural integrity of the HTTP message based on RFC 7230 standards. In terms of offensive security frameworks, this flaw facilitates techniques associated with MITRE ATT&CK T1559: Inter-Process Communication or more specifically aspects of Request Smuggling (T1187) and Header Injection attacks. The ability to control request framing decisions is particularly dangerous as it undermines the trust boundary between client-supplied data and server-side configuration, allowing for potential denial-of-service conditions through malformed large payloads or unauthorized access via manipulated authentication headers embedded in the body.
Mitigation strategies must focus on enforcing strict adherence to HTTP protocol standards within the add-on's parsing engine. The primary remediation involves modifying the request parser to strictly identify the end of the header section using the correct delimiter and immediately cease any further interpretation of subsequent bytes as header fields. Developers should implement a state machine that transitions from header parsing mode to body reading mode upon detecting the double newline sequence, ensuring no further regex or string searches for key-value pairs are performed on the payload data. Additionally, input validation routines should be strengthened to reject requests where non-standard characters appear in positions that violate RFC 7230 syntax rules before they reach the core logic. It is also advisable to deploy a Web Application Firewall configured with signatures capable of detecting HTTP request smuggling patterns and header injection attempts as an additional layer of defense while the underlying code is patched. Regular security audits focusing on network protocol parsing libraries are recommended to prevent similar structural vulnerabilities in future updates.