Security advisory

{
  "id": "38c2379cbb1f1ab42e749c7036a29bdfb268b1be21852bd1b8f399619cc37047",
  "url": "https://osv.dev/vulnerability/CVE-2021-41186",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-41186",
    "summary": "Fluentd collects events from various data sources and writes them to files to help unify logging infrastructure. The parser_apache2 plugin in Fluentd v0.14.14 to v1.14.1 suffers from a regular expression denial of service (ReDoS) vulnerability. A broken apache log with a certain pattern of string can spend too much time in a regular expression, resulting in the potential for a DoS attack. This issue is patched in version 1.14.2 There are two workarounds available. Either don't use parser_apache2 for parsing logs (which cannot guarantee generated by Apache), or put patched version of parser_apache2.rb into /etc/fluent/plugin directory (or any other directories specified by the environment variable `FLUENT_PLUGIN` or `--plugin` option of fluentd).",
    "evidence": "osv:CVE-2021-41186",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2021-41186",
      "aliases": [
        "BIT-fluentd-2021-41186",
        "CVE-2021-41186",
        "GHSA-hwhf-64mh-r662"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/fluent/fluentd",
              "type": "GIT",
              "events": [
                {
                  "introduced": "85d51905accfce7158470f3e4ab99641a4cfd5e9"
                },
                {
                  "last_affected": "6a3b2216c13b55861c8679a0c2e02436f426774f"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:fluentd:fluentd:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0.14.14"
                      },
                      {
                        "last_affected": "1.14.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.14.1",
            "v1.14.0",
            "v1.14.0.rc",
            "v1.13.3",
            "v1.13.2",
            "v1.13.1",
            "v1.13.0",
            "v1.12.3",
            "v1.12.2",
            "v1.12.1",
            "v1.12.0",
            "v1.12.0.rc2",
            "v1.12.0.rc1",
            "v1.11.5",
            "v1.11.4",
            "v1.11.3",
            "v1.11.2",
            "v1.11.1",
            "v1.11.0",
            "v1.10.4",
            "v1.10.3",
            "v1.10.2",
            "v1.10.1",
            "v1.10.0",
            "v1.9.3",
            "v1.9.2",
            "v1.9.1",
            "v1.9.0",
            "v1.9.0.rc2",
            "v1.9.0.rc1",
            "v1.8.1",
            "v1.8.0",
            "v1.2.3",
            "v1.8.0.rc3",
            "v1.8.0.rc2",
            "v1.8.0.rc1",
            "v1.7.3",
            "v1.7.2",
            "v1.7.1",
            "v1.7.0",
            "v1.7.0.rc1",
            "v1.6.2",
            "v1.6.1",
            "v1.6.0",
            "v1.5.1",
            "v1.5.0",
            "v1.5.0.rc1",
            "v1.4.2",
            "v1.4.1",
            "v1.4.0",
            "v1.3.3",
            "v1.3.2",
            "v1.3.1",
            "v1.3.0",
            "v1.2.6",
            "v1.2.5",
            "v1.2.5.rc1",
            "v1.2.4",
            "v1.2.4.rc1",
            "v1.2.2",
            "v1.2.1",
            "v1.2.0",
            "v1.2.0.pre1",
            "v1.1.2",
            "v1.1.3",
            "v1.1.1",
            "v1.1.0",
            "v1.0.2",
            "v1.0.1",
            "v1.0.0",
            "v0.14.25",
            "v1.0.0.rc1",
            "v0.14.24",
            "v0.14.23",
            "v0.14.23.rc1",
            "v0.14.22",
            "v0.14.22.rc2",
            "v0.14.22.rc1",
            "v0.14.21",
            "v0.14.20",
            "v0.14.20.rc1",
            "v0.14.19",
            "v0.14.18",
            "v0.14.17",
            "v0.14.16",
            "v0.14.15",
            "v0.14.14"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-41186.json"
          }
        }
      ],
      "modified": "2026-10-20T10:54:57.713193479Z",
      "provider": "osv",
      "references": [
        "https://github.com/github/securitylab-vulnerabilities/blob/52dc4a2a828c6dc24231967c2937ad92038184a9/vendor_reports/GHSL-2021-102-fluent-fluentd.md",
        "https://github.com/fluent/fluentd/blob/master/CHANGELOG.md#v1142",
        "https://github.com/fluent/fluentd/security/advisories/GHSA-hwhf-64mh-r662"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-41186",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 386557,
  "published_at": "2021-10-29T14:15:07.73+00:00"
}