yawkat LZ4 Java: LZ4FrameInputStream reallocates block buffers for every frame, allowing CPU and GC amplification from small inputs

{
  "id": "35c2f3b9286fb6d78c240cc4ac5bd17f89cab05b4699e09761e54c84f289e596",
  "url": "https://osv.dev/vulnerability/GHSA-gm45-99xc-r7wv",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "yawkat LZ4 Java: LZ4FrameInputStream reallocates block buffers for every frame, allowing CPU and GC amplification from small inputs",
    "summary": "### Summary `LZ4FrameInputStream` allocates two new buffers of the frame's maximum block size, up to 4 MiB each, every time it reads a frame header. Because concatenated frames are read by default, an input made of many minimal empty frames forces about 8 MiB of zeroed heap allocation for every 11 input bytes. ### Details In `net.jpountz.lz4.LZ4FrameInputStream.readHeader()`: ```java maxBlockSize = frameInfo.getBD().getBlockMaximumSize(); compressedBuffer = new byte[maxBlockSize]; // Reused during different compressions rawBuffer = new byte[maxBlockSize]; buffer = ByteBuffer.wrap(rawBuffer); ``` This runs for every frame, and the previous frame's arrays are never reused. A valid 11-byte frame consists of the magic number, FLG `0x60`, BD `0x70` (4 MiB blocks), the header checksum, and an immediate end mark. It carries no data, yet triggers the full 8 MiB allocation. `new LZ4FrameInputStream(in)` reads concatenated frames by default. In local measurements on JDK 25, 10,000 such frames (110 KB of input) took about 8 seconds of CPU to read, roughly 70 seconds per MiB of input. This was similar under G1, Parallel, Serial and ZGC. A legitimate stream costs orders of magnitude less per input byte. ### Impact Applications that decode attacker-controlled LZ4 frame data with `LZ4FrameInputStream` can be made to spend large amounts of CPU and GC time relative to the input size. Live heap stays bounded at about 8 MiB and the stream produces no output, so decompressed-size limits do not h",
    "evidence": "osv:GHSA-gm45-99xc-r7wv",
    "products": [
      {
        "name": {
          "value": "at.yawk.lz4:lz4-java",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.11.4",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "1.10.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.10.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.10.2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.10.3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.10.4",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.11.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.11.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.11.2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.11.3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.8.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.9.0",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "org.lz4:lz4-java",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.4",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.4.0",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.4.1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.5.0",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.5.1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.6.0",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.7.0",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.7.1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.8.0",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.8.1",
            "evidence": "/affected/1/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-gm45-99xc-r7wv",
      "aliases": [
        "CVE-2026-106450",
        "GHSA-gm45-99xc-r7wv"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.11.4"
                }
              ]
            }
          ],
          "package": {
            "name": "at.yawk.lz4:lz4-java",
            "purl": "pkg:maven/at.yawk.lz4/lz4-java",
            "ecosystem": "Maven"
          },
          "versions": [
            "1.10.0",
            "1.10.1",
            "1.10.2",
            "1.10.3",
            "1.10.4",
            "1.11.0",
            "1.11.1",
            "1.11.2",
            "1.11.3",
            "1.8.1",
            "1.9.0"
          ],
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-gm45-99xc-r7wv/GHSA-gm45-99xc-r7wv.json",
            "last_known_affected_version_range": "<= 1.11.3"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "1.8.1"
                }
              ]
            }
          ],
          "package": {
            "name": "org.lz4:lz4-java",
            "purl": "pkg:maven/org.lz4/lz4-java",
            "ecosystem": "Maven"
          },
          "versions": [
            "1.4",
            "1.4.0",
            "1.4.1",
            "1.5.0",
            "1.5.1",
            "1.6.0",
            "1.7.0",
            "1.7.1",
            "1.8.0",
            "1.8.1"
          ],
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-gm45-99xc-r7wv/GHSA-gm45-99xc-r7wv.json"
          }
        }
      ],
      "modified": "2026-10-07T20:45:05.906321924Z",
      "provider": "osv",
      "references": [
        "https://github.com/yawkat/lz4-java/security/advisories/GHSA-gm45-99xc-r7wv",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-106450",
        "https://github.com/yawkat/lz4-java/commit/2acc0ec1ead226145c62a817c18c8ed49233a283",
        "https://github.com/yawkat/lz4-java",
        "https://github.com/yawkat/lz4-java/releases/tag/v1.11.4"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-770"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-06T20:17:27Z",
        "github_reviewed_at": "2026-10-07T20:35:40Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-106450",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 97267,
  "published_at": "2026-10-07T20:35:40+00:00"
}