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of outdated or incompatible HTTP protocol versions in the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.
-
System Configuration
Turn all pages to non-cacheable.
Source: MITRE CWE-444
124 results · Clear filters · Feed
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High 7.8
Skipper: opaAuthorizeRequestWithBody filter bypasses OPA policy on Transfer-Encoding: chunked / HTTP/2 requests
Skipper is an HTTP router and reverse proxy for service composition. Prior to 0.26.10, zalando/skipper's OpenPolicyAgent integration silently bypasses request-body inspection on HTTP/1.1 Transfer-Encoding: chunked and HTTP/2 requests that omit the content-len…
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High 7.4
Inconsistent Interpretation of HTTP Requests in CICS Transaction Gateway for Multiplatforms.
IBM CICS Transaction Gateway for Multiplatforms 9.1, 9.2, 9.3, and 10.1 IBM WebSphere Application Server 9.0, and 8.5 and IBM WebSphere Application Server - Liberty 17.0.0.3 through 26.0.0.6 are affected by an HTTP request smuggling vulnerability.
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High 7.2
IBM WebSphere Application Server Liberty is affected by a an arbitrary file read vulnerability
IBM WebSphere Application Server - Liberty 17.0.0.3 through 26.0.0.6 is affected by an arbitrary file read vulnerability with the restConnector-2.0 feature enabled.
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High 7.5
Envoy: HTTP/3 to HTTP/1 request smuggling via headers-only request with nonzero Content-Length
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, Envoy can translate a downstream HTTP/3 request that is complete at the transport layer (HEADERS with FIN / headers-only close…
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High 8.1
Caddy: FastCGI header normalization bypass in `forward_auth copy_headers`
Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, forward_auth copy_headers deletes the exact client-supplied identity header before copying the trusted value from the auth gateway. But when the request later goes through php_f…
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High 7.4
IBM WebSphere Application Server and WebSphere Application Server Liberty are affected by multiple vulnerabilities
IBM WebSphere Application Server 9.0 and 8.5 and IBM WebSphere Application Server - Liberty 17.0.0.3 through 26.0.0.6 are vulnerable to HTTP request smuggling. A remote attacker could smuggle a specially crafted request to the application server thereby allow…
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High 7.5
PHP Standard Library: HTTP/2 server-side missing content-length validation enables request smuggling
PHP Standard Library (PSL) is set of APIs covering async, collections, networking, I/O, cryptography, terminal UI, etc. In versions 6.1.0, 6.1.1 and 6.2.0, the Psl\H2\ServerConnection does not validate that the total bytes received in DATA frames match the co…
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High 7.5
IBM WebSphere Application Server and WebSphere Application Server Liberty are affected by multiple vulnerabilities when using when using Web Server Plug-ins
IBM Web Server Plug-ins for WebSphere Application Server and WebSphere Liberty 8.5, 9.0 IBM WebSphere Application Server and WebSphere Application Server Liberty are vulnerable to HTTP request smuggling in the Web Server Plug-ins through a specially crafted r…
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High 7.3
Netty: HttpClientCodec response desynchronization
Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpClientCodec pairs each inbound response with an outbound request by queue.poll() once per response, including for 1xx. If the client pipelines G…
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High 7.5
Gazelle versions through 0.49 for Perl allows HTTP Request Smuggling via Improper Header Precedence
Gazelle versions through 0.49 for Perl allows HTTP Request Smuggling via Improper Header Precedence. Gazelle incorrectly prioritizes "Content-Length" over "Transfer-Encoding: chunked" when both headers are present in an HTTP request. Per RFC 7230 3.3.3, Trans…
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High 7.5
Starman versions before 0.4018 for Perl allows HTTP Request Smuggling via Improper Header Precedence
Starman versions before 0.4018 for Perl allows HTTP Request Smuggling via Improper Header Precedence. Starman incorrectly prioritizes "Content-Length" over "Transfer-Encoding: chunked" when both headers are present in an HTTP request. Per RFC 7230 3.3.3, Tran…
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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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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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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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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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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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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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High 8.2
Libsoup: libsoup: duplicate host header handling causes host-parsing discrepancy (first- vs last-value wins)
A flaw in libsoup’s HTTP header handling allows multiple Host: headers in a request and returns the last occurrence for server-side processing. Common front proxies often honor the first Host: header, so this mismatch can cause vhost confusion where a proxy r…
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High 7.5
Outsystems Platform Server 11.18.1.37828 allows attackers to cause a denial of service via a crafted content-length val…
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High 7.5
Vulnerability in the Oracle Configurator product of Oracle E-Business Suite (component: Runtime UI). Supported versions…
KEV Oct 20, 2025 -
High 7.5
Next.js DoS vulnerability via cache poisoning
Next.js is a React framework for building full-stack web applications. From versions 15.0.4-canary.51 to before 15.1.8, a cache poisoning bug leading to a Denial of Service (DoS) condition was found in Next.js. This issue does not impact customers hosted on V…
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High 8.6
CVE-2025-41235: Spring Cloud Gateway Server Forwards Headers from Untrusted Proxies
Spring Cloud Gateway Server forwards the X-Forwarded-For and Forwarded headers from untrusted proxies.
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High 7.4
Request Smuggling Vulnerability in Pingora
A request smuggling vulnerability identified within Pingora’s proxying framework, pingora-proxy, allows malicious HTTP requests to be injected via manipulated request bodies on cache HITs, leading to unauthorized request execution and potential cache poisonin…
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High 8.7
HTTP Request Smuggling in Google Cloud Classic Application Load Balancer due to Improper Chunked Encoding Validation
A request smuggling vulnerability existed in the Google Cloud Classic Application Load Balancer due to improper handling of chunked-encoded HTTP requests. This allowed attackers to craft requests that could be misinterpreted by backend servers. The issue was …
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High 7.7
An issue in OpenResty lua-nginx-module v.0.10.26 and before allows a remote attacker to conduct HTTP request smuggling …
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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 9.2.0 through 9.2.9, from 10.0.0 through 10.0.4. Users are recommended to upgrade to version 9.2.10 or 10.0.5, which fixes the is…
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High 7.5CVE-2025-31137 Public exploit
Remix and React Router allow URL manipulation via Host / X-Forwarded-Host headers
React Router is a multi-strategy router for React bridging the gap from React 18 to React 19. There is a vulnerability in Remix/React Router that affects all Remix 2 and React Router 7 consumers using the Express adapter. Basically, this vulnerability allows …
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High 7.5
HTTP Request Smuggling in netease-youdao/qanything
HTTP Request Smuggling vulnerability in netease-youdao/qanything version 1.4.1 allows attackers to exploit inconsistencies in the interpretation of HTTP requests between a proxy and a server. This can lead to unauthorized access, bypassing security controls, …
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High 7.5
HTTP Request Smuggling in benoitc/gunicorn
Gunicorn version 21.2.0 does not properly validate the value of the 'Transfer-Encoding' header as specified in the RFC standards, which leads to the default fallback method of 'Content-Length,' making it vulnerable to TE.CL request smuggling. This vulnerabili…
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High 7.1
Envoyproxy: openshift service mesh envoy http header sanitization bypass leading to dos and unauthorized access
A flaw was found in OpenShift Service Mesh 2.6.3 and 2.5.6. Rate-limiter avoidance, access-control bypass, CPU and memory exhaustion, and replay attacks may be possible due to improper HTTP header sanitization in Envoy.
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High 7.4
Io.quarkus.http/quarkus-http-core: quarkus http cookie smuggling
A flaw was found in Quarkus-HTTP, which incorrectly parses cookies with certain value-delimiting characters in incoming requests. This issue could allow an attacker to construct a cookie value to exfiltrate HttpOnly cookie values or spoof arbitrary additional…
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High 7.4
Undertow: cookie smuggling/spoofing
A flaw was found in Undertow, which incorrectly parses cookies with certain value-delimiting characters in incoming requests. This issue could allow an attacker to construct a cookie value to exfiltrate HttpOnly cookie values or spoof arbitrary additional coo…
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High 7.5
GNOME libsoup before 3.6.0 allows HTTP request smuggling in some configurations because '\0' characters at the end of h…
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High 7.5
kmqtt v0.2.7 is vulnerable to Denial of Service (DoS) due to a Null Pointer Exception. A remote attacker can cause the …
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High 8.9
HTTP Request Smuggling in Looker
An HTTP Request Smuggling vulnerability in Looker allowed an unauthorized attacker to capture HTTP responses destined for legitimate users. There are two Looker versions that are hosted by Looker: * Looker (Google Cloud core) was found to be vulnerable. This …