+V4.2 HTTP Message Structure Validation
---+V4.2.1 Verify that all application components (including load balancers, firewalls, and application …
---+V4.2.2 Verify that when generating HTTP messages, the Content-Length header field does not conflict with …
---+V4.2.3 Verify that the application does not send nor accept HTTP/2 or HTTP/3 messages with …
---+V4.2.4 Verify that the application only accepts HTTP/2 and HTTP/3 requests where the header fields and …
---+V4.2.5 Verify that, if the application (backend or frontend) builds and sends requests, it uses …

V4.2 HTTP Message Structure Validation

This section explains how the structure and header fields of an HTTP message should be validated to prevent attacks such as request smuggling, response splitting, header injection, and denial of service via overly long HTTP messages.

These requirements are relevant for general HTTP message processing and generation, but are especially important when converting HTTP messages between different HTTP versions.

1. Resumen

Título	Estándar
V4.2.1 Verify that all application components (including load balancers, firewalls, and application …	Verify that all application components (including load balancers, firewalls, and application servers) determine boundaries of incoming HTTP messages using the appropriate mechanism for the HTTP version to prevent HTTP request smuggling. In HTTP/1.x, if a Transfer-Encoding header field is present, the Content-Length header must be ignored per RFC 2616. When using HTTP/2 or HTTP/3, if a Content-Length header field is present, the receiver must ensure that it is consistent with the length of the DATA frames.
V4.2.2 Verify that when generating HTTP messages, the Content-Length header field does not conflict with …	Verify that when generating HTTP messages, the Content-Length header field does not conflict with the length of the content as determined by the framing of the HTTP protocol, in order to prevent request smuggling attacks.
V4.2.3 Verify that the application does not send nor accept HTTP/2 or HTTP/3 messages with …	Verify that the application does not send nor accept HTTP/2 or HTTP/3 messages with connection-specific header fields such as Transfer-Encoding to prevent response splitting and header injection attacks.
V4.2.4 Verify that the application only accepts HTTP/2 and HTTP/3 requests where the header fields and …	Verify that the application only accepts HTTP/2 and HTTP/3 requests where the header fields and values do not contain any CR (\r), LF (\n), or CRLF (\r\n) sequences, to prevent header injection attacks.
V4.2.5 Verify that, if the application (backend or frontend) builds and sends requests, it uses …	Verify that, if the application (backend or frontend) builds and sends requests, it uses validation, sanitization, or other mechanisms to avoid creating URIs (such as for API calls) or HTTP request header fields (such as Authorization or Cookie), which are too long to be accepted by the receiving component. This could cause a denial of service, such as when sending an overly long request (e.g., a long cookie header field), which results in the server always responding with an error status.

1.1 Referencias

1.2 Requisitos identificados

1.3 Regulaciones relacionadas

2. Requisitos identificados

Requisitos
Fuente	Requisito

3. Regulaciones relacionadas

Regulaciones
Fuente	Regulación

OWASP -
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- OWASP Application Security Verification Standard (ASVS) 5.0.0, Mai 2025, aus OWASP/ASVS: © 2008-2025 The OWASP Foundation, lizenziert unter CC BY-SA 4.0. Änderungen: in Abschnitte aufgeteilt und in das GRCA-Format umgewandelt, der Wortlaut unverändert. Diese Bearbeitungen stehen ebenfalls unter CC BY-SA 4.0.
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