{"id":"CVE-2021-21409","published":"2021-03-30T15:05:17Z","modified":"2026-10-08T21:13:55Z","title":"Possible request smuggling in HTTP/2 due missing validation of content-length","vendor":"netty","product":"netty","tier":"tail","description":{"text":"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) before version 4.1.61.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 translated to HTTP/1.1. This is a followup of GHSA-wm47-8v5p-wjpj/CVE-2021-21295 which did miss to fix this one case. This was fixed as part of 4.1.61.Final.","provenance":"source","from":"CVE.org"},"cvss":{"score":5.9,"severity":"MEDIUM","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","provenance":"source","from":"CVE.org CNA"},"epss":{"score":0.04935,"percentile":0.92142,"provenance":"source"},"cwes":[{"id":"CWE-444","name":"Inconsistent Interpretation of HTTP Requests"}],"references":[{"url":"https://github.com/netty/netty/security/advisories/GHSA-f256-j965-7f32","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/netty/netty/security/advisories/GHSA-wm47-8v5p-wjpj","tags":["x_refsource_MISC"]},{"url":"https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-21295","tags":["x_refsource_MISC"]},{"url":"https://github.com/netty/netty/commit/b0fa4d5aab4215f3c22ce6123dd8dd5f38dc0432","tags":["x_refsource_MISC"]},{"url":"https://www.debian.org/security/2021/dsa-4885","tags":["vendor-advisory","x_refsource_DEBIAN"]},{"url":"https://lists.apache.org/thread.html/r70c3a7bfa904f06a1902f4df20ee26e4f09a46b8fd3eb304dc57a2de%40%3Cdev.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/ra66e93703e3f4bd31bdfd0b6fb0c32ae96b528259bb1aa2b6d38e401%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r2732aa3884cacfecac4c54cfaa77c279ba815cad44b464a567216f83%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r0ca82fec33334e571fe5b388272260778883e307e15415d7b1443de2%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r823d4b27fcba8dad5fe945bdefce3ca5a0031187966eb6ef3cc22ba9%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r101f82d8f3b5af0bf79aecbd5b2dd3b404f6bb51d1a54c2c3d29bed9%40%3Cnotifications.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/rf521ff2be2e2dd38984174d3451e6ee935c845948845c8fccd86371d%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r5cbea8614812289a9b98d0cfc54b47f54cef424ac98d5e315b791795%40%3Cnotifications.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/rdd206d9dd7eb894cc089b37fe6edde2932de88d63a6d8368b44f5101%40%3Ccommits.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/rac8cf45a1bab9ead5c9a860cbadd6faaeb7792203617b6ec3874736d%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r4a98827bb4a7edbd69ef862f2351391845697c40711820d10df52ca5%40%3Ccommits.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r69efd8ef003f612c43e4154e788ca3b1f837feaacd16d97854402355%40%3Ccommits.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r4b8be87acf5b9c098a2ee350b5ca5716fe7afeaf0a21a4ee45a90687%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/re4b0141939370304d676fe23774d0c6fbc584b648919825402d0cb39%40%3Cnotifications.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/rdd5715f3ee5e3216d5e0083a07994f67da6dbb9731ce9e7a6389b18e%40%3Ccommits.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r1b3cb056364794f919aaf26ceaf7423de64e7fdd05a914066e7d5219%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/rf38e4dcdefc7c59f7ba0799a399d6d6e37b555d406a1dfc2fcbf0b35%40%3Ccommits.pulsar.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r61564d86a75403b854cdafee67fc69c8b88c5f6802c2c838f4282cc8%40%3Ccommits.pulsar.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r7879ddcb990c835c6b246654770d836f9d031dee982be836744e50ed%40%3Ccommits.pulsar.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r5baac01f9e06c40ff7aab209d5751b3b58802c63734e33324b70a06a%40%3Cissues.flink.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/ra64d56a8a331ffd7bdcd24a9aaaeeedeacd5d639f5a683389123f898%40%3Cdev.flink.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/rd8f72411fb75b98d366400ae789966373b5c3eb3f511e717caf3e49e%40%3Cissues.flink.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/re7c69756a102bebce8b8681882844a53e2f23975a189363e68ad0324%40%3Cissues.flink.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/rbde2f13daf4911504f0eaea43eee4f42555241b5f6d9d71564b6c5fa%40%3Cjira.kafka.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r855b4b6814ac829ce2d48dd9d8138d07f33387e710de798ee92c011e%40%3Cissues.flink.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/rafc77f9f03031297394f3d372ccea751b23576f8a2ae9b6b053894c5%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/re39391adcb863f0e9f3f15e7986255948f263f02e4700b82453e7102%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/re9e6ed60941da831675de2f8f733c026757fb4fa28a7b6c9f3dfb575%40%3Cdev.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/re1911e05c08f3ec2bab85744d788773519a0afb27272a31ac2a0b4e8%40%3Cnotifications.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/redef0fb5474fd686781007de9ddb852b24f1b04131a248d9a4789183%40%3Cnotifications.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r0b09f3e31e004fe583f677f7afa46bd30110904576c13c5ac818ac2c%40%3Cissues.flink.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r602e98daacc98934f097f07f2eed6eb07c18bfc1949c8489dc7bfcf5%40%3Cissues.flink.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://www.oracle.com//security-alerts/cpujul2021.html","tags":["x_refsource_MISC"]},{"url":"https://security.netapp.com/advisory/ntap-20210604-0003/","tags":["x_refsource_CONFIRM"]},{"url":"https://lists.apache.org/thread.html/rba2a9ef1d0af882ab58fadb336a58818495245dda43d32a7d7837187%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/raa413040db6d2197593cc03edecfd168732e697119e6447b0a25d525%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/rf148b2bf6c2754153a8629bc7495e216bd0bd4c915695486542a10b4%40%3Cnotifications.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/rd4a6b7dec38ea6cd28b6f94bd4b312629a52b80be3786d5fb0e474bc%40%3Cissues.kudu.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/rca0978b634a0c3ebee4126ec29c7f570b165fae3f8f3658754c1cbd3%40%3Cissues.kudu.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/rf934292a4a1c189827f625d567838d2c1001e4739b158638d844105b%40%3Cissues.kudu.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/ra655e5cec74d1ddf62adacb71d398abd96f3ea2c588f6bbf048348eb%40%3Cissues.kudu.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r4ea2f1a9d79d4fc1896e085f31fb60a21b1770d0a26a5250f849372d%40%3Cissues.kudu.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r6dac9bd799ceac499c7a7e152a9b0dc7f2fe7f89ec5605d129bb047b%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r31044fb995e894749cb821c6fe56f487c16a97028e6e360e59f09d58%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r5f2f120b2b8d099226473db1832ffb4d7c1d6dc2d228a164bf293a8e%40%3Cissues.zookeeper.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]}],"priority":{"score":22.6,"factors":[{"name":"EPSS percentile","points":18.43},{"name":"CVSS severity","points":4.13}]},"vendorSlug":"netty","referencesTotal":59,"affectedVersions":[{"vendor":"netty","product":"netty","versions":["< 4.1.61.Final"]}],"affected":[{"ecosystem":"Maven","package":"io.netty:netty-codec-http2","vulnerableRanges":[">=4.0.0, <4.1.61.Final"],"patched":["4.1.61.Final"],"from":["GHSA-f256-j965-7f32"],"provenance":"source"},{"ecosystem":"Maven","package":"org.jboss.netty:netty","vulnerableRanges":["<4.0.0"],"patched":[],"from":["GHSA-f256-j965-7f32"],"provenance":"source"},{"ecosystem":"Maven","package":"io.netty:netty","vulnerableRanges":["<4.0.0"],"patched":[],"from":["GHSA-f256-j965-7f32"],"provenance":"source"}],"euvd":{"id":"EUVD-2021-0647","exploited":false,"provenance":"source"},"lineage":{"familyId":"fam-netty-io-netty-netty-codec-http2-cve-2021-21295","parents":[{"from":"CVE-2021-21295","to":"CVE-2021-21409","relation":"successor","confidence":"high","kind":"lineage","evidence":[{"kind":"osv-related","provenance":"source","id":"GHSA-wm47-8v5p-wjpj","via":"related"},{"kind":"osv-related","provenance":"source","id":"GHSA-f256-j965-7f32","via":"reference","url":"https://github.com/netty/netty/security/advisories/GHSA-wm47-8v5p-wjpj"},{"kind":"version-step","provenance":"source","package":"Maven:io.netty:netty-codec-http2","fromFixed":"4.1.60.Final","toFixed":"4.1.61.Final","daysApart":21},{"kind":"similar","provenance":"machine","score":0.35,"basis":"same package + description similarity"}]}],"children":[{"from":"CVE-2021-21409","to":"CVE-2022-0552","relation":"incomplete-fix","confidence":"high","kind":"lineage","evidence":[{"kind":"text","provenance":"source","relation":"incomplete-fix","quote":"A flaw was found in the original fix for the netty-codec-http CVE-2021-21409, where the OpenShift Logging openshift-logging/elasticsearch6-rhel8 container was incomplete.","from":"CVE.org","in":"CVE-2022-0552"}]}],"packageHistory":[{"cve":"CVE-2021-21295","published":"2021-03-09","fixed":"4.1.60.Final","kev":false},{"cve":"CVE-2021-21409","published":"2021-03-30","fixed":"4.1.61.Final","kev":false},{"cve":"CVE-2025-55163","published":"2025-08-13","fixed":"4.2.4.Final","kev":false},{"cve":"CVE-2026-33871","published":"2026-03-27","fixed":"4.2.11.Final","kev":false},{"cve":"CVE-2026-42587","published":"2026-05-13","fixed":"4.2.13.Final","kev":false}],"package":"Maven:io.netty:netty-codec-http2"}}