CVE-2026-33870 — Netty: HTTP Request Smuggling via Chunked Extension Quoted-String Parsing

Affected: netty, Red Hat Cryostat 4 on RHEL 9, Red Hat AMQ Broker 7.12.7, Red Hat AMQ Broker 7.13.5, Red Hat AMQ Broker 7.14.0, Red Hat Build of Apache Camel 4.14 for Quarkus 3.27, Red Hat build of Apache Camel 4.18.1 for Spring Boot 3.5.14, Red Hat build of Quarkus 3.20.6, Red Hat build of Quarkus 3.27.3, Red Hat Data Grid 8.6.1 and 26 more

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. Versions 4.1.132.Final and 4.2.10.Final fix the issue.

GHSA-2c5c-chwr-9hqw — Netty HTTP/3 QPACK literal unbounded allocation

Affected: Maven: io.netty:netty-codec-http3

### Summary When Netty decodes HTTP/3 headers, it sometimes runs `new byte[length]` using a length from the wire before checking that many bytes are really there. A small malicious header can claim a huge length (on the order of a gigabyte).

### Details When decoding header blocks, the non-Huffman branch of `io.netty.handler.codec.http3.QpackDecoder#decodeHuffmanEncodedLiteral` may execute `new byte[length]` for a string literal before verifying that length bytes are actually present in the compressed field section. The wire encoding allows a very large length to be expressed in few bytes. There is no check that `length <= in.readableBytes()` before `new byte[length]`.

### PoC The test below constructs a small HTTP/3 HEADERS frame whose QPACK section decodes to a ~1 GiB non-Huffman name length and is used to observe server-side failure; it illustrates how little wire data can target `new byte[length]`.

```java @Test public void test() throws Exception { EventLoopGroup group = new MultiThreadIoEventLoopGroup(1, NioIoHandler.newFactory()); try { X509Bundle cert = new CertificateBuilder() .subject("cn=localhost") .setIsCertificateAuthority(true) .buildSelfSigned();

QuicSslContext serverContext = QuicSslContextBuilder.forServer(cert.toTempPrivateKeyPem(), null, cert.toTempCertChainPem()) .applicationProtocols(Http3.supportedApplicationProtocols())…

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CVE-2026-33870 — Netty: HTTP Request Smuggling via Chunked Extension Quoted-String Parsing

GHSA-2c5c-chwr-9hqw — Netty HTTP/3 QPACK literal unbounded allocation