{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.8.4"
      },
      "package": {
        "ecosystem": "RubyGems",
        "name": "fluent-plugin-s3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.7.0"
            },
            {
              "fixed": "1.8.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44162"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-26T17:02:19Z",
    "nvd_published_at": null,
    "severity": "LOW"
  },
  "details": "The `fluent-plugin-s3` plugin (specifically the `in_s3` input plugin) supports reading and decompressing heavily compressed files (such as `gzip`, `lzma2`, and `lzop`) from Amazon S3. \nIt was discovered that the plugin read the entire decompressed payload into memory at once without enforcing a strict size limit.\n\nIf an attacker has sufficient permissions to upload files to the monitored S3 bucket, they can upload a maliciously crafted, highly compressed file.\nWhen Fluentd attempts to decompress this file, it will expand to an excessive size and it will consume significant system resources.\n\n### Impact\nThis vulnerability allows for a **Denial of Service (DoS)** attack via memory exhaustion. \nThe rapid memory consumption during decompression can lead to an Out-of-Memory kill of the Fluentd process by the operating system, \nThis results in the disruption of all log collection on the affected node.\n\n### Patches\nv1.8.5\n\n### Workarounds\nIf an immediate upgrade is not possible, mitigate the risk by applying strict IAM access controls:\n\n1. Restrict Bucket Access\n   * Ensure that write (PUT) access to the S3 bucket monitored by `in_s3` is strictly limited to trusted services and administrators. Prevent any public or untrusted uploads to the S3 bucket.",
  "id": "GHSA-xv9w-7v6q-hpjh",
  "modified": "2026-06-26T17:02:19Z",
  "published": "2026-06-26T17:02:19Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/fluent/fluent-plugin-s3/security/advisories/GHSA-xv9w-7v6q-hpjh"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fluent/fluent-plugin-s3/commit/e085aee001d15bcc4bd073507e74075e30550fd0"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/fluent/fluent-plugin-s3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "fluent-plugin-s3 Vulnerable to Denial of Service (DoS) via Decompression Bomb in `in_s3`"
}