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of outdated or incompatible HTTP protocol versions in the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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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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Medium 4.8
Akamai Ghost on Akamai CDN edge servers before 2025-11-17 has a chunked request body processing error that can result i…
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Medium 6.9
HTTP Header Smuggling via Trailer Merge
lighttpd1.4.80 incorrectly merged trailer fields into headers after http request parsing. This behavior can be exploited to conduct HTTP Header Smuggling attacks. Successful exploitation may allow an attacker to: * Bypass access control rules * Inject unsafe …
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Medium 6.9
HTTP Desynchronisation in Vertex AI for certain third-party models
Connection desynchronization between an HTTP proxy and the model backend. The fixes were rolled out for all proxies in front of impacted models by 2025-09-28. Users do not need to take any action.
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Critical 9.9
ASP.NET Security Feature Bypass Vulnerability
Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an authorized attacker to bypass a security feature over a network.
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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 -
Medium 6.3
Http4s vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section
Http4s is a Scala interface for HTTP services. In versions from 1.0.0-M1 to before 1.0.0-M45 and before 0.23.31, http4s is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section. This vulnerability could enable attackers to bypa…
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Medium 6.9
WatchGuard Firebox Authentication Portal Request Smuggling Vulnerability
An HTTP Request Smuggling [CWE-444] vulnerability in the Authentication portal of WatchGuard Fireware OS allows a remote attacker to evade request parameter sanitation and perform a reflected self-Cross-Site Scripting (XSS) attack. WatchGuard does not believe…
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Critical 9.8CVE-2025-56266 Scanner template
A Host Header Injection vulnerability in Avigilon ACM v7.10.0.20 allows attackers to execute arbitrary code via supplyi…
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Low 2.9
Netty is vulnerable to request smuggling due to incorrect parsing of chunk extensions
Netty is an asynchronous event-driven network application framework for development of maintainable high performance protocol servers and clients. In versions 4.1.124.Final, and 4.2.0.Alpha3 through 4.2.4.Final, Netty incorrectly accepts standalone newline ch…
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Medium 6.3
Eventlet affected by HTTP request smuggling in unparsed trailers
Eventlet is a concurrent networking library for Python. Prior to version 0.40.3, the Eventlet WSGI parser is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer sections. This vulnerability could enable attackers to, bypass front-end…
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Medium 4.0
Akamai Ghost before 2025-07-21 allows HTTP Request Smuggling via an OPTIONS request that has an entity body, because th…
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Medium —
mitmproxy binaries embed a vulnerable python-hyper/h2 dependency
mitmproxy 12.1.1 and below embed python-hyper/h2 ≤ v4.2.0, which has a gap in its HTTP/2 header validation. This enables request smuggling attacks when mitmproxy is in a configuration where it translates HTTP/2 to HTTP/1. For example, this affects reverse pro…
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Medium 4.0CVE-2025-32094 Public exploit
An issue was discovered in Akamai Ghost, as used for the Akamai CDN platform before 2025-03-26. Under certain circumsta…
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Medium 4.5
EspoCRM is vulnerable to access denial through double slash in URI corrupting router cache
EspoCRM is a web application with a frontend designed as a single-page application and a REST API backend written in PHP. In versions 9.1.6 and below, if a user loads Espo in the browser with double slashes (e.g https://domain//#Admin) and the webserver does …
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Low 1.7
AIOHTTP is vulnerable to HTTP Request/Response Smuggling through incorrect parsing of chunked trailer sections
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.12.14, the Python parser is vulnerable to a request smuggling vulnerability due to not parsing trailer sections of an HTTP request. If a pure Python version of …
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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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Low 3.7
Next.js cache poisoning due to omission of Vary header
Next.js is a React framework for building full-stack web applications. In Next.js App Router from 15.3.0 to before 15.3.3 and Vercel CLI from 41.4.1 to 42.2.0, a cache poisoning vulnerability was found. The issue allowed page requests for HTML content to retu…
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Medium 6.5
Ruby WEBrick read_header HTTP Request Smuggling Vulnerability
Ruby WEBrick read_header HTTP Request Smuggling Vulnerability. This vulnerability allows remote attackers to smuggle arbitrary HTTP requests on affected installations of Ruby WEBrick. This issue is exploitable when the product is deployed behind an HTTP proxy…
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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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Medium 6.5CVE-2025-23167 Public exploit
A flaw in Node.js 20's HTTP parser allows improper termination of HTTP/1 headers using `\r\n\rX` instead of the require…
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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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Medium 5.4
Varnish Cache before 7.6.3 and 7.7 before 7.7.1, and Varnish Enterprise before 6.0.13r14, allow client-side desync via …
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Critical 9.1
Radware Cloud Web Application Firewall (WAF) before 2025-05-07 allows remote attackers to bypass firewall filters by pl…
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Critical 9.1
h11 accepts some malformed Chunked-Encoding bodies
h11 is a Python implementation of HTTP/1.1. Prior to version 0.16.0, a leniency in h11's parsing of line terminators in chunked-coding message bodies can lead to request smuggling vulnerabilities under certain conditions. This issue has been patched in versio…
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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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Critical 9.1
croogo Host header injection
An issue in croogo v.3.0.2 allows an attacker to perform Host header injection via the feed.rss component.
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Medium 5.9
Query smuggling in ch-go library
When using the ch-go library, under a specific condition when the query includes a large, uncompressed malicious external data, it is possible for an attacker in control of such data to smuggle another query packet into the connection stream.
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Critical 9.1
Request smuggling due to acceptance of invalid chunked data in net/http
The net/http package improperly accepts a bare LF as a line terminator in chunked data chunk-size lines. This can permit request smuggling if a net/http server is used in conjunction with a server that incorrectly accepts a bare LF as part of a chunk-ext.
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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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Medium 4.7
IBM Cognos Controller HTTP response smuggling
IBM Cognos Controller 11.0.0 through 11.1.0 is vulnerable to a Client-Side Desync (CSD) attack where an attacker could exploit a desynchronized browser connection that could lead to further cross-site scripting (XSS) attacks.
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Medium 5.4
Varnish Cache before 7.6.2 and Varnish Enterprise before 6.0.13r10 allow client-side desync via HTTP/1 requests.
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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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Medium 5.3
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Critical 10.0
HTTP Response Smuggling Vulnerability in libhv
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in ithewei libhv allows HTTP Response Smuggling.This issue affects libhv: through 1.3.3.
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Medium 6.8
In Perfex Crm < 3.2.1, an authenticated attacker can send a crafted HTTP POST request to the affected upload_sales_file…