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Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads to Event-Loop Thread Hang

Type: advisorySources: OSV

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the `Bzip2Decoder` handler in Netty's compression codec pipeline is vulnerable to a denial-of-service attack through a malformed bzip2 stream that permanently captures the event-loop thread in an infinite loop. The vulnerability exists in the run-length encoding (RLE) state machine within [`Bzip2BlockDecompressor.read()`]. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-59901
Confirmed fixed CVEs
Not specified
Updated in this feed
6 Nov 2026, 09:01 UTC · Revision 1

Source evidence

Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads to Event-Loop Thread Hang

core-osv · Original source

Published 29 Jul 2026, 17:48 UTC

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the `Bzip2Decoder` handler in Netty's compression codec pipeline is vulnerable to a denial-of-service attack through a malformed bzip2 stream that permanently captures the event-loop thread in an infinite loop. The vulnerability exists in the run-length encoding (RLE) state machine within [`Bzip2BlockDecompressor.read()`]. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

osv:CVE-2026-59901
Complete source record
{
  "id": "79f0706aa7aa9e3154b4bb220245cfcfb1448b40d88e8c5b0b9ebf7173471329",
  "url": "https://osv.dev/vulnerability/CVE-2026-59901",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads to Event-Loop Thread Hang",
    "summary": "Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the `Bzip2Decoder` handler in Netty's compression codec pipeline is vulnerable to a denial-of-service attack through a malformed bzip2 stream that permanently captures the event-loop thread in an infinite loop. The vulnerability exists in the run-length encoding (RLE) state machine within [`Bzip2BlockDecompressor.read()`]. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.",
    "evidence": "osv:CVE-2026-59901",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-59901",
      "aliases": [
        "CVE-2026-59901",
        "GHSA-558v-64gr-wgg4"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/netty/netty",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "fca0764703b3bb59c6e6dc5d29c6d9710d35c0e6"
                },
                {
                  "introduced": "09e64d259c99be8b5b2a471a78f11e65eb82598a"
                },
                {
                  "fixed": "3703d79669ee024f6483c9d8697ac58ba546df33"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.1.136"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "4.2.0"
                      },
                      {
                        "fixed": "4.2.16"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
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            "netty-4.2.10.Final",
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            "netty-4.2.3.Final",
            "netty-4.2.2.Final",
            "netty-4.1.122.Final",
            "netty-4.2.1.Final",
            "netty-4.1.121.Final",
            "netty-4.1.120.Final",
            "netty-4.2.0.Final",
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-59901.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:47.229818992Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59901.json",
        "https://github.com/netty/netty/security/advisories/GHSA-558v-64gr-wgg4",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-59901"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-835"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59901.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-59901",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 515037,
  "published_at": "2026-07-29T17:48:39.621+00:00"
}