{"id":"CVE-2026-44162","aliases":["EUVD-2026-77705","GHSA-xv9w-7v6q-hpjh"],"status":"published","title":"fluent-plugin-s3: Denial of Service (DoS) via Decompression Bomb in `in_s3`","description":"fluent-plugin-s3 is an Amazon S3 input and output plugin for Fluentd. From 0.7.0 to 1.8.4, the in_s3 input plugin reads the entire decompressed payload of gzip, lzma2, and lzop objects into memory without enforcing a decompression_size_limit. An attacker with permission to upload objects to the monitored S3 bucket can provide a highly compressed object that expands excessively when Fluentd processes it. The resulting memory exhaustion can cause the operating system to terminate the Fluentd process and disrupt all log collection on the affected node. This issue is fixed in version 1.8.5.","severity":{"version":"3.1","score":2.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","level":"low","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00483,"percentile":0.41966,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-409","CWE-770"],"published":"2026-06-26T17:02:19Z","modified":"2026-10-28T02:30:34Z","fixes":[{"ecosystem":"RubyGems","package":"fluent-plugin-s3","fixed_in":["1.8.5"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"RubyGems","package":"fluent-plugin-s3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.7.0"},{"last_affected":"1.8.4"},{"fixed":"1.8.5"}]}]},{"source":"osv","ecosystem":"RubyGems","package":"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"]}],"products":[{"vendor":"fluent","product":"fluent-plugin-s3"}],"references":[{"url":"https://github.com/fluent/fluent-plugin-s3/security/advisories/GHSA-xv9w-7v6q-hpjh","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/fluent/fluent-plugin-s3/commit/e085aee001d15bcc4bd073507e74075e30550fd0","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/fluent/fluent-plugin-s3/releases/tag/v1.8.5","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/advisories/GHSA-xv9w-7v6q-hpjh"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44162.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44162","tags":["advisory"]},{"url":"https://github.com/fluent/fluent-plugin-s3","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-44162","title":"fluent-plugin-s3: Denial of Service (DoS) via Decompression Bomb in `in_s3`","description":"fluent-plugin-s3 is an Amazon S3 input and output plugin for Fluentd. From 0.7.0 to 1.8.4, the in_s3 input plugin reads the entire decompressed payload of gzip, lzma2, and lzop objects into memory without enforcing a decompression_size_limit. An attacker with permission to upload objects to the monitored S3 bucket can provide a highly compressed object that expands excessively when Fluentd processes it. The resulting memory exhaustion can cause the operating system to terminate the Fluentd process and disrupt all log collection on the affected node. This issue is fixed in version 1.8.5.","status":"published","published":"2026-09-14T17:45:37.057Z","modified":"2026-09-14T18:14:18.27Z","cvss":[{"version":"3.1","score":2.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","level":"low","assessor":"cna"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T13:43:00.288193Z"}],"euvd":[{"id":"EUVD-2026-77705","description":"fluent-plugin-s3 is an Amazon S3 input and output plugin for Fluentd. From 0.7.0 to 1.8.4, the in_s3 input plugin reads the entire decompressed payload of gzip, lzma2, and lzop objects into memory without enforcing a decompression_size_limit. An attacker with permission to upload objects to the monitored S3 bucket can provide a highly compressed object that expands excessively when Fluentd processes it. The resulting memory exhaustion can cause the operating system to terminate the Fluentd process and disrupt all log collection on the affected node. This issue is fixed in version 1.8.5.","status":"published","published":"2026-09-14T17:45:37Z","modified":"2026-09-14T18:14:18Z","cvss":[{"version":"3.1","score":2.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","level":"low"}],"updated_at":"2026-11-02T17:28:19.730872Z"}],"ghsa":[{"id":"GHSA-xv9w-7v6q-hpjh","title":"fluent-plugin-s3 Vulnerable to Denial of Service (DoS) via Decompression Bomb in `in_s3`","description":"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.","status":"published","published":"2026-06-26T17:02:19Z","modified":"2026-06-26T17:02:21Z","cvss":[{"version":"3.1","score":2.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","level":"low"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:40:33.778544Z"}],"nvd":[{"id":"CVE-2026-44162","description":"fluent-plugin-s3 is an Amazon S3 input and output plugin for Fluentd. From 0.7.0 to 1.8.4, the in_s3 input plugin reads the entire decompressed payload of gzip, lzma2, and lzop objects into memory without enforcing a decompression_size_limit. An attacker with permission to upload objects to the monitored S3 bucket can provide a highly compressed object that expands excessively when Fluentd processes it. The resulting memory exhaustion can cause the operating system to terminate the Fluentd process and disrupt all log collection on the affected node. This issue is fixed in version 1.8.5.","status":"published","published":"2026-09-14T18:17:47.513Z","modified":"2026-09-30T19:57:08.043Z","cvss":[{"version":"3.1","score":2.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","level":"low","assessor":"secondary"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T14:12:46.980627Z"}],"osv":[{"id":"CVE-2026-44162","title":"fluent-plugin-s3: Denial of Service (DoS) via Decompression Bomb in `in_s3`","description":"fluent-plugin-s3 is an Amazon S3 input and output plugin for Fluentd. From 0.7.0 to 1.8.4, the in_s3 input plugin reads the entire decompressed payload of gzip, lzma2, and lzop objects into memory without enforcing a decompression_size_limit. An attacker with permission to upload objects to the monitored S3 bucket can provide a highly compressed object that expands excessively when Fluentd processes it. The resulting memory exhaustion can cause the operating system to terminate the Fluentd process and disrupt all log collection on the affected node. This issue is fixed in version 1.8.5.","status":"published","published":"2026-09-14T17:45:37.057Z","modified":"2026-10-28T02:30:34.387287402Z","cvss":[{"version":"3.1","score":2.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","level":"low"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T15:45:04.820169Z"},{"id":"GHSA-xv9w-7v6q-hpjh","title":"fluent-plugin-s3 Vulnerable to Denial of Service (DoS) via Decompression Bomb in `in_s3`","description":"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.","status":"published","published":"2026-06-26T17:02:19Z","modified":"2026-09-10T03:51:09.895284828Z","cvss":[{"version":"3.1","score":2.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","level":"low"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:47:00.604718Z"}]}}