CVE Vulnerabilities


Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Published: Feb 08, 2024 | Modified: Feb 29, 2024
CVSS 3.x
CVSS 2.x

Request smuggling vulnerability in HTTP server in Apache bRPC 0.9.5~1.7.0 on all platforms allows attacker to smuggle request.

Vulnerability Cause Description:

The http_parser does not comply with the RFC-7230 HTTP 1.1 specification.

Attack scenario: If a message is received with both a Transfer-Encoding and a Content-Length header field, such a message might indicate an attempt to perform request smuggling or response splitting. One particular attack scenario is that a bRPC made http server on the backend receiving requests in one persistent connection from frontend server that uses TE to parse request with the logic that chunk is contained in the TE field. in that case an attacker can smuggle a request into the connection to the backend server. 

Solution: You can choose one solution from below:

  1. Upgrade bRPC to version 1.8.0, which fixes this issue. Download link:
  2. Apply this patch:


The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

Affected Software

Name Vendor Start Version End Version
Brpc Apache 0.9.5 *

Extended Description

HTTP requests or responses (“messages”) can be malformed or unexpected in ways that cause web servers or clients to interpret the messages in different ways than intermediary HTTP agents such as load balancers, reverse proxies, web caching proxies, application firewalls, etc. For example, an adversary may be able to add duplicate or different header fields that a client or server might interpret as one set of messages, whereas the intermediary might interpret the same sequence of bytes as a different set of messages. For example, discrepancies can arise in how to handle duplicate headers like two Transfer-encoding (TE) or two Content-length (CL), or the malicious HTTP message will have different headers for TE and CL. The inconsistent parsing and interpretation of messages can allow the adversary to “smuggle” a message to the client/server without the intermediary being aware of it. This weakness is usually the result of the usage of outdated or incompatible HTTP protocol versions in the HTTP agents.

Potential Mitigations