CVE-2026-44890: Netty codec redis Netty Has Unbounded Direct Memory Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6ghj-frrj-jjj3",
  "modified" : "2026-06-12T19:27:16Z",
  "published" : "2026-06-08T19:02:09Z",
  "aliases" : [ "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "io.netty:netty-codec-redis"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.2.0.Final"
      }, {
        "fixed" : "4.2.15.Final"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.2.14.Final"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "io.netty:netty-codec-redis"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.135.Final"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.134.Final"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "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" : "PACKAGE",
    "url" : "https://github.com/netty/netty"
  }, {
    "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-08T19:02:09Z",
    "nvd_published_at" : "2026-06-11T22:16:56Z"
  }
}