Advisories for Maven/Io.netty/Netty-All package

2026

Inconsistent Interpretation of HTTP Requests

Netty's HttpServerCodec pairs each outbound response with an inbound request by calling pollMethod() once per response, including for 1xx informational responses. If a client pipelines an HTTP/1.1 GET carrying an Expect: 100-continue header followed by a HEAD request, the 100 Continue response consumes the queued GET method, so the subsequent 200 OK for the GET is paired with HEAD and its body is dropped, while the following 200 OK for …

Incorrect Behavior Order: Validate Before Canonicalize

A flaw was found in Netty RtspDecoder. The RtspMethods.valueOf() function incorrectly strips trailing control bytes from method tokens in Real-Time Streaming Protocol (RTSP) requests. A remote attacker can exploit this by sending a specially crafted RTSP request, leading to method-token smuggling. This vulnerability allows an attacker to bypass method-based access controls and can also be used to launder malicious requests through Netty-based RTSP proxies, making them appear legitimate to backend …

Inconsistent Interpretation of HTTP Requests

A flaw was found in Netty. A remote unauthenticated attacker can exploit a vulnerability in Netty's HTTP/1 to HTTP/2 conversion process. When an HTTP/1 request includes both an absolute-form request-target and a conflicting Host header, Netty incorrectly prioritizes the Host header for the HTTP/2 :authority field, discarding the original request-target authority. This inconsistency can allow an attacker to bypass security controls in Netty-based proxies or gateways, potentially leading to unauthorized …

Improper Input Validation

A flaw was found in Netty's HTTP/2 codec. When converting HTTP/1 CONNECT requests to HTTP/2, the component incorrectly uses the Host header instead of the CONNECT authority-form request-target for the tunnel authority. A remote attacker can exploit this by supplying a different Host header, leading to a malformed HTTP/2 CONNECT request. This can bypass security controls such as tunnel allow-lists or egress policies, resulting in integrity loss. The netty-all artifact …

Improper Input Validation

A flaw was found in Netty. A remote attacker could exploit this vulnerability by sending specially crafted HTTP/2 or HTTP/3 Extended CONNECT requests. Netty's HTTP-object conversion path incorrectly processes these requests as regular HTTP/1.1 CONNECT requests, leading to a loss of critical protocol and path information. This misinterpretation can allow attackers to bypass security policies, such as routing or authorization logic, in applications that rely on Netty for HTTP/2 or …

Improper Validation of Certificate with Host Mismatch

Netty disables TLS hostname verification on the SslProvider.OPENSSL client path when a plain (non-extended) X509TrustManager is used and Unsafe-based trust-manager wrapping is unavailable (Java 25+). In this configuration the OpenSSL client does not perform hostname verification, allowing a man-in-the-middle attacker to present a certificate issued for a different hostname that is accepted without validation. The netty-all artifact is a shaded jar that embeds the vulnerable ReferenceCountedOpenSslClientContext class from version 4.1.1 …

2023

False positive

The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.

Allocation of Resources Without Limits or Throttling

Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. The SniHandler can allocate up to 16MB of heap for each channel during the TLS handshake. When the handler or the channel does not have an idle timeout, it can be used to make a TCP server using the SniHandler to allocate 16MB of heap. The SniHandler class is a handler …

2022

Uncontrolled Recursion

Netty project is an event-driven asynchronous network application framework. In versions prior to 4.1.86.Final, a StackOverflowError can be raised when parsing a malformed crafted message due to an infinite recursion. This issue is patched in version 4.1.86.Final. There is no workaround, except using a custom HaProxyMessageDecoder.

2021

Uncontrolled Resource Consumption

The Bzip2 decompression decoder function does not allow setting size restrictions on the decompressed output data (which affects the allocation size used during decompression). All users of Bzip2Decoder are affected. The malicious input can trigger an OOME and so a DoS attack

Inconsistent Interpretation of HTTP Requests (HTTP Request Smuggling)

Netty is an open-source, asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. In Netty (io.netty:netty-codec-http2) Final there is a vulnerability that enables request smuggling. The content-length header is not correctly validated if the request only uses a single Http2HeaderFrame with the endStream set to to true. This could lead to request smuggling if the request is proxied to a remote peer and …

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