{"id":"GHSA-xv9w-7v6q-hpjh","summary":"fluent-plugin-s3 Vulnerable to Denial of Service (DoS) via Decompression Bomb in `in_s3`","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.","aliases":["CVE-2026-44162"],"modified":"2026-07-03T18:29:44.360692058Z","published":"2026-06-26T17:02:19Z","related":["CGA-5qxv-g25f-qv59"],"database_specific":{"github_reviewed_at":"2026-06-26T17:02:19Z","nvd_published_at":null,"cwe_ids":["CWE-770"],"severity":"LOW","github_reviewed":true},"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"}],"affected":[{"package":{"name":"fluent-plugin-s3","ecosystem":"RubyGems","purl":"pkg:gem/fluent-plugin-s3"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.7.0"},{"fixed":"1.8.5"}]}],"versions":["0.7.0","0.7.1","0.7.2","0.8.0","0.8.0.rc1","0.8.1","0.8.2","0.8.3","0.8.4","0.8.5","0.8.6","0.8.7","0.8.8","1.0.0","1.0.0.rc1","1.0.0.rc2","1.0.0.rc3","1.0.0.rc4","1.0.0.rc5","1.0.0.rc6","1.0.0.rc7","1.0.0.rc8","1.1.0","1.1.1","1.1.10","1.1.11","1.1.2","1.1.3","1.1.4","1.1.5","1.1.6","1.1.7","1.1.8","1.1.9","1.2.0","1.2.1","1.3.0","1.3.1","1.3.2","1.3.3","1.3.4","1.4.0","1.5.0","1.5.1","1.6.0","1.6.1","1.7.0","1.7.1","1.7.2","1.8.0","1.8.1","1.8.2","1.8.3","1.8.4"],"database_specific":{"last_known_affected_version_range":"\u003c= 1.8.4","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-xv9w-7v6q-hpjh/GHSA-xv9w-7v6q-hpjh.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L"}]}