Weakness (CWE)
CWE-444: Inconsistent Interpretation of HTTP Requests
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.
More detail
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of outdated or incompatible HTTP protocol versions in the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.
How to prevent it (4 mitigations)
-
Implementation
Use a web server that employs a strict HTTP parsing procedure, such as Apache [REF-433].
-
Implementation
Use only SSL communication.
-
Implementation
Terminate the client session after each request.
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System Configuration
Turn all pages to non-cacheable.
Source: MITRE CWE-444
406 results · Feed
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Low 3.7
Libsoup: libsoup: http request smuggling via duplicate content-length headers
A request smuggling vulnerability exists in libsoup's HTTP/1 header parsing logic. The soup_message_headers_append_common() function in libsoup/soup-message-headers.c unconditionally appends each header value without validating for duplicate or conflicting Co…
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Low 3.7
HCL BigFix Service Management (SM) is susceptible to HTTP Request Smuggling
HCL BigFix Service Management is susceptible to HTTP Request Smuggling. HTTP request smuggling vulnerabilities arise when websites route HTTP requests through web servers with inconsistent HTTP parsing. HTTP Smuggling exploits inconsistencies in request pars…
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Critical 9.0
@fastify/reply-from vulnerable to connection header abuse enabling stripping of proxy-added headers
@fastify/reply-from v12.6.1 and earlier and @fastify/http-proxy v11.4.3 and earlier process the client's Connection header after the proxy has added its own headers via rewriteRequestHeaders. This allows attackers to retroactively strip proxy-added headers fr…
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High 7.4CVE-2026-2332 Public exploit
HTTP Request Smuggling via Chunked Extension Quoted-String Parsing
In Eclipse Jetty, the HTTP/1.1 parser is vulnerable to request smuggling when chunk extensions are used, similar to the "funky chunks" techniques outlined here: * https://w4ke.info/2025/06/18/funky-chunks.html * https://w4ke.info/2025/10/29/funky-chunks-2.htm…
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Medium 4.8CVE-2026-40175 Public exploit
Axios has Unrestricted Cloud Metadata Exfiltration via Header Injection Chain
Axios is a promise based HTTP client for the browser and Node.js. Versions prior to 1.15.0 and 0.3.1 are vulnerable to a specific gadget-style attack chain in which prototype pollution in a third-party dependency may be leveraged to inject unsanitized header …
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High 7.5CVE-2026-24880 Public exploit
Apache Tomcat: Request smuggling via invalid chunk extension
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in Apache Tomcat via invalid chunk extension. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.18, from 10.1.0-M1 through 10.1.52, from 9.0.0.M1 throug…
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High 7.5
Tinyproxy HTTP request parsing desynchronization via case-sensitive Transfer-Encoding handling
Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer function uses strcmp to compare the header value against "chunked", even…
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High 7.5
Apache Traffic Server: Malformed chunked message body allows request smuggling
Apache Traffic Server allows request smuggling if chunked messages are malformed. This issue affects Apache Traffic Server: from 9.0.0 through 9.2.12, from 10.0.0 through 10.1.1. Users are recommended to upgrade to version 9.2.13 or 10.1.2, which fix the iss…
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Medium 5.3
Security Vulnerabilities have been found in IBM Verify Identity Access and IBM Security Verify Access
IBM Verify Identity Access Container 11.0 through 11.0.2 and IBM Security Verify Access Container 10.0 through 10.0.9.1 and IBM Verify Identity Access 11.0 through 11.0.2 and IBM Security Verify Access 10.0 through 10.0.9.1 IBM Security Verify could allow a r…
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Medium 5.3
Security Vulnerabilities have been found in IBM Verify Identity Access and IBM Security Verify Access
IBM Verify Identity Access Container 11.0 through 11.0.2 and IBM Security Verify Access Container 10.0 through 10.0.9.1 and IBM Verify Identity Access 11.0 through 11.0.2 and IBM Security Verify Access 10.0 through 10.0.9.1 IBM Security Verify could allow a r…
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Medium 6.3
AIOHTTP: Duplicate Host header accepted
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, multiple Host headers were allowed in aiohttp. This issue has been patched in version 3.13.4.
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Medium 4.8
cpp-httplib: HTTP Request Smuggling via Unconsumed GET Request Body
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.40.0, cpp-httplib is vulnerable to HTTP Request Smuggling. The server's static file handler serves GET responses without consuming the request body. On HTTP/1…
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High 7.5
Netty: HTTP Request Smuggling via Chunked Extension Quoted-String Parsing
Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, Netty incorrectly parses quoted strings in HTTP/1.1 chunked transfer encoding extension values, enabling request smuggling attacks. Vers…
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High 8.7
Undertow: undertow: request smuggling via malformed http request headers
A flaw was found in Undertow. When Undertow receives an HTTP request where the first header line starts with one or more spaces, it incorrectly processes the request by stripping these leading spaces. This behavior, which violates HTTP standards, can be explo…
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High 8.7
Undertow: undertow: request smuggling via `\r\r\r` as a header block terminator
A flaw was found in Undertow. A remote attacker can exploit this vulnerability by sending `\r\r\r` as a header block terminator. This can be used for request smuggling with certain proxy servers, such as older versions of Apache Traffic Server and Google Clou…
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High 8.7
Undertow: undertow: request smuggling via inconsistent header parsing
A flaw was found in Undertow. This vulnerability allows a remote attacker to construct specially crafted requests where header names are parsed differently by Undertow compared to upstream proxies. This discrepancy in header interpretation can be exploited to…
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Critical 9.8
Mitigation bypass in the Networking: HTTP component
Mitigation bypass in the Networking: HTTP component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
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Low 2.9
HTTP Request Smuggling in visualfc/liteide
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in visualfc liteide (liteidex/src/3rdparty/qjsonrpc/src/http-parser modules). This vulnerability is associated with program files http_parser.C. This issue affects …
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Medium 6.3CVE-2026-29057 Public exploit
Next.js: HTTP request smuggling in rewrites
Next.js is a React framework for building full-stack web applications. Starting in version 9.5.0 and prior to versions 15.5.13 and 16.1.7, when Next.js rewrites proxy traffic to an external backend, a crafted `DELETE`/`OPTIONS` request using `Transfer-Encodin…
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High 7.0
Request smuggling via first-wins Content-Length parsing in inets httpd
Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling') vulnerability in Erlang OTP (inets httpd module) allows HTTP Request Smuggling. This vulnerability is associated with program files lib/inets/src/http_server/httpd_request.erl and program…
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Medium 6.5
undici is vulnerable to Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Undici allows duplicate HTTP Content-Length headers when they are provided in an array with case-variant names (e.g., Content-Length and content-length). This produces malformed HTTP/1.1 requests with multiple conflicting Content-Length values on the wire. Wh…
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Medium 6.3
Cap'n Proto: Integer overflow in KJ-HTTP chunk size
Cap'n Proto is a data interchange format and capability-based RPC system. Prior to 1.4.0, when using Transfer-Encoding: chunked, if a chunk's size parsed to a value of 2^64 or larger, it would be truncated to a 64-bit integer. In theory, this bug could enable…
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Medium 6.3
Cap'n Proto has an integer overflow in KJ-HTTP
Cap'n Proto is a data interchange format and capability-based RPC system. Prior to 1.4.0, a negative Content-Length value was converted to unsigned, treating it as an impossibly large length instead. In theory, this bug could enable HTTP request/response smug…
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Critical 9.3
TinyWeb: Integer Overflow in `_Val` (HTTP Request Smuggling)
TinyWeb is a web server (HTTP, HTTPS) written in Delphi for Win32. Prior to version 2.03, an integer overflow vulnerability in the string-to-integer conversion routine (_Val) allows an unauthenticated remote attacker to bypass Content-Length restrictions and …
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Critical 9.3CVE-2026-2835 Public exploit
HTTP Request Smuggling via HTTP/1.0 and Transfer-Encoding Misparsing
An HTTP Request Smuggling vulnerability (CWE-444) has been found in Pingora's parsing of HTTP/1.0 and Transfer-Encoding requests. The issue occurs due to improperly allowing HTTP/1.0 request bodies to be close-delimited and incorrect handling of multiple Tran…
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Critical 9.3
HTTP Request Smuggling via Premature Upgrade
An HTTP request smuggling vulnerability (CWE-444) was found in Pingora's handling of HTTP/1.1 connection upgrades. The issue occurs when a Pingora proxy reads a request containing an Upgrade header, causing the proxy to pass through the rest of the bytes on t…
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Medium 4.3
Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software VPN Web Services Client-Side Request Smuggling Vulnerability
A vulnerability in the VPN web services component of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to conduct browser-based attacks agai…
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Medium 4.0
Akamai Ghost on Akamai CDN edge servers before 2026-02-06 mishandles processing of custom hop-by-hop HTTP headers, wher…
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Medium 6.9
Cloud Suite and Privilege Access Service– HTTP request smuggling vulnerability
Improper Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling') in Delinea Inc. Cloud Suite and Privileged Access Service. If you're not using the latest Server Suite agents, this fix requires that you upgrade to Server Suite 2023.1 (agent 6.…
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Medium 5.2
An inconsistent interpretation of http requests ('http request smuggling') vulnerability in Fortinet FortiOS 7.6.0, For…
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Medium 5.3CVE-2026-1801 Public exploit
Libsoup: libsoup: http request smuggling via malformed chunk headers
A flaw was found in libsoup, an HTTP client/server library. This HTTP Request Smuggling vulnerability arises from non-RFC-compliant parsing in the soup_filter_input_stream_read_line() logic, where libsoup accepts malformed chunk headers, such as lone line fee…
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Medium 5.3
Libsoup: soupserver: denial of service via http request smuggling
A flaw was found in SoupServer. This HTTP request smuggling vulnerability occurs because SoupServer improperly handles requests that combine Transfer-Encoding: chunked and Connection: keep-alive headers. A remote, unauthenticated client can exploit this by se…
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Medium 6.9
HTTP Request/Response Smuggling in Altitude Communication Server
Illegal HTTP request traffic vulnerability (CL.0) in Altitude Communication Server, caused by inconsistent analysis of multiple HTTP requests over a single Keep-Alive connection using Content-Length headers. This can cause a desynchronization of requests betw…
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Medium 6.9
Eclipse Vert.x Web static handler file access denial
The Vert.x Web static handler component cache can be manipulated to deny the access to static files served by the handler using specifically crafted request URI. The issue comes from an improper implementation of the C. rule of section 5.2.4 of RFC3986 and is…
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High 8.9
h3 v1 has Request Smuggling (TE.TE) issue
H3 is a minimal H(TTP) framework built for high performance and portability. Prior to 1.15.5, there is a critical HTTP Request Smuggling vulnerability. readRawBody is doing a strict case-sensitive check for the Transfer-Encoding header. It explicitly looks fo…
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Low 2.7
AIOHTTP Regex Mismatch Allows Unicode in ASCII-Only Protocol Fields
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Versions 3.13.2 and below contain parser logic which allows non-ASCII decimals to be present in the Range header. There is no known impact, but there is the possibility that there…
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Medium 6.3
AIOHTTP's Unicode processing of header values could cause parsing discrepancies
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Versions 3.13.2 and below of the Python HTTP parser may allow a request smuggling attack with the presence of non-ASCII characters. If a pure Python version of AIOHTTP is installe…
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High —
flagd: Multiple Go Runtime CVEs Impact Security and Availability
### Summary In 2025, several vulnerabilities in the Go Standard Library were disclosed, impacting Go-based applications like flagd (the evaluation engine for OpenFeature). These CVEs primarily focus on Denial of Service (DoS) through resource exhaustion and R…
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Medium 6.3
HTTP Request Smuggling in Quest Coexistence Manager for Notes
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in Quest Coexistence Manager for Notes (Free/Busy Connector modules) allows HTTP Request Smuggling via the Content-Length-Transfer-Encoding (CL.TE) attack vector. T…
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Medium 6.9
Member Login Script 3.3 Client-Side Request Desynchronization Vulnerability
Member Login Script 3.3 contains a client-side desynchronization vulnerability that allows attackers to manipulate HTTP request handling by exploiting Content-Length header parsing. Attackers can send crafted POST requests with smuggled secondary requests to …