{"cve":"CVE-2021-41186","nvd":{"published":"2021-10-29T14:15:07.730","modified":"2026-06-17T04:08:03.120","status":"Modified","description":"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).","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-400"],"references":["https://github.com/fluent/fluentd/blob/master/CHANGELOG.md#v1142","https://github.com/fluent/fluentd/security/advisories/GHSA-hwhf-64mh-r662","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"],"products":["fluentd:fluentd"],"source":"nvd","synced_at":"2026-10-19T21:24:39.218183596+00:00"},"epss":{"cve":"CVE-2021-41186","score":0.02215,"percentile":0.82632,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-hwhf-64mh-r662","url":"https://osv.dev/vulnerability/GHSA-hwhf-64mh-r662","summary":"ReDoS vulnerability in parser_apache2","modified":"2026-07-08T06:28:53.596219161Z","packages":[{"ecosystem":"RubyGems","name":"fluentd","purl":"pkg:gem/fluentd","ranges":[">=0.14.14 <1.14.2"],"fixed":["1.14.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}