{"id":"CVE-2026-44890","aliases":["GHSA-6ghj-frrj-jjj3"],"url":"https://o3.security/vulnerability/CVE-2026-44890","summary":"Netty has Unbounded Direct Memory Consumption in its RedisDecoder","details":"### Summary\nAn attacker can cause DoS by sending crafted Redis payloads across multiple connections without `\\r\\n`. This exhausts the server's direct memory pool (OutOfDirectMemoryError), preventing legitimate connections from being processed.\n\n### Details\nio.netty.handler.codec.redis.RedisDecoder decodes the length of bulk strings and array headers using the `decodeLength` method. This method reads bytes from the network until it encounters a `\\n` character. However, it does not enforce any maximum length check while buffering the bytes if the `\\n` character is not found. An attacker can exploit this by sending a continuous stream of digits (e.g., `$1111...`) without ever sending a `\\n`.\n\nTo cause a true Denial of Service, an attacker must open multiple concurrent connections and distribute the unbounded payloads among them.\n\nAccording to the RESP specification (https://redis.io/docs/latest/develop/reference/protocol-spec/), all parts of the protocol are strictly terminated with `\\r\\n`. Furthermore, the length prefix itself is an integer representation that must fit within standard numeric limits (e.g., a 64-bit signed integer). Therefore, a stream of digits exceeding these bounds without `\\r\\n` is a protocol violation and should be rejected immediately rather than buffered indefinitely.\n\n### Impact\nDenial of Service due to memory exhaustion. Any application using Netty's RedisDecoder to handle untrusted Redis traffic is vulnerable.","published":"2026-06-11T20:52:50.980Z","modified":"2026-09-20T11:45:53.256289720Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.00461,"percentile":0.39043,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Maven","name":"io.netty:netty-codec-redis","fixedVersion":"4.2.15.Final"},{"ecosystem":"Maven","name":"io.netty:netty-codec-redis","fixedVersion":"4.1.135.Final"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.1.135.Final"},{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.2.15.Final"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44890.json"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:37390"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:41951"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:50085"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:53644"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:53645"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:53646"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-44890"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44890.json"},{"type":"ADVISORY","url":"https://github.com/netty/netty/security/advisories/GHSA-6ghj-frrj-jjj3"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44890"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2488053"},{"type":"PACKAGE","url":"https://github.com/netty/netty"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-20T11:45:53.256289720Z"}}