{"id":"CVE-2021-41186","aliases":["BIT-fluentd-2021-41186","EUVD-2021-2358","GHSA-hwhf-64mh-r662","openSUSE-SU-2024:11795-1","openSUSE-SU-2024:13155-1","openSUSE-SU-2024:14072-1","openSUSE-SU-2025:15115-1","openSUSE-SU-2026:10346-1"],"status":"published","title":"ReDoS vulnerability in parser_apache2","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).","severity":{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.02215,"percentile":0.82862,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-400"],"published":"2021-10-29T13:40:10Z","modified":"2026-10-20T10:54:57Z","fixes":[{"ecosystem":"RubyGems","package":"fluentd","fixed_in":["1.14.2"],"sources":["ghsa","osv"]},{"ecosystem":"Bitnami","package":"fluentd","fixed_in":["1.14.2"],"sources":["osv"]},{"ecosystem":"openSUSE:Tumbleweed","package":"rubygem-fluentd","fixed_in":["1.14.4-1.1","1.17.0-1.1","1.17.1-1.3","1.17.1-1.5"],"sources":["osv"]},{"ecosystem":"openSUSE:Tumbleweed","package":"ruby3.2-rubygem-fluentd","fixed_in":["1.15.3-1.4"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"RubyGems","package":"fluentd","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.14.14"},{"fixed":"1.14.2"}]}]},{"source":"osv","ecosystem":"Bitnami","package":"fluentd","ranges":[{"type":"SEMVER","events":[{"introduced":"0.14.14"},{"fixed":"1.14.2"}]}]},{"source":"osv","ecosystem":"RubyGems","package":"fluentd","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.14.14"},{"fixed":"1.14.2"}]}],"versions":["0.14.14","0.14.15","0.14.16","0.14.17","0.14.18","0.14.19","0.14.20","0.14.20.rc1","0.14.21","0.14.22","0.14.22.rc1","0.14.22.rc2","0.14.23","0.14.23.rc1","0.14.24","0.14.25","1.0.0","1.0.0.rc1","1.0.1","1.0.2","1.1.0","1.1.1","1.1.2","1.1.3","1.10.0","1.10.1","1.10.2","1.10.3","1.10.4","1.11.0","1.11.1","1.11.2","1.11.3","1.11.4","1.11.5","1.12.0","1.12.0.rc1","1.12.0.rc2","1.12.1","1.12.2","1.12.3","1.12.4","1.13.0","1.13.1","1.13.2","1.13.3","1.14.0","1.14.0.rc","1.14.1","1.2.0","1.2.0.pre1","1.2.1","1.2.2","1.2.3","1.2.4","1.2.4.rc1","1.2.5","1.2.5.rc1","1.2.6","1.3.0","1.3.1","1.3.2","1.3.3","1.4.0","1.4.1","1.4.2","1.5.0","1.5.0.rc1","1.5.1","1.5.2","1.6.0","1.6.1","1.6.2","1.6.3","1.7.0","1.7.0.rc1","1.7.1","1.7.2","1.7.3","1.7.4","1.8.0","1.8.0.rc1","1.8.0.rc2","1.8.0.rc3","1.8.1","1.9.0","1.9.0.rc1","1.9.0.rc2","1.9.1","1.9.2","1.9.3"]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"rubygem-fluentd","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.14.4-1.1"}]}]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"ruby3.2-rubygem-fluentd","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.15.3-1.4"}]}]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"rubygem-fluentd","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.17.0-1.1"}]}]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"rubygem-fluentd","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.17.1-1.3"}]}]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"rubygem-fluentd","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.17.1-1.5"}]}]}],"products":[{"vendor":"fluent","product":"fluentd"},{"vendor":"fluentd","product":"fluentd"}],"references":[{"url":"https://github.com/fluent/fluentd/security/advisories/GHSA-hwhf-64mh-r662","tags":["x_refsource_CONFIRM","x_transferred","Third Party Advisory","advisory","web"]},{"url":"https://github.com/fluent/fluentd/blob/master/CHANGELOG.md#v1142","tags":["x_refsource_MISC","x_transferred","Release Notes","Third Party Advisory","advisory","web"]},{"url":"https://github.com/github/securitylab-vulnerabilities/blob/52dc4a2a828c6dc24231967c2937ad92038184a9/vendor_reports/GHSL-2021-102-fluent-fluentd.md","tags":["x_refsource_MISC","x_transferred","Broken Link","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-41186","tags":["web","advisory"]},{"url":"https://github.com/fluent/fluentd/commit/5482a3d049dab351de0be68f4b4bc562319d8511","tags":["web"]},{"url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/fluentd/CVE-2021-41186.yml","tags":["web"]},{"url":"https://github.com/advisories/GHSA-hwhf-64mh-r662"},{"url":"https://github.com/fluent/fluentd","tags":["package"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2021-41186","tags":["web"]},{"url":"https://lists.opensuse.org/archives/list/security-announce@lists.opensuse.org/thread/WIPFBYYKQWWOA7STXAOX3HXCCSJWJEXF/","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2021-41186","title":"ReDoS vulnerability in parser_apache2","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).","status":"published","published":"2021-10-29T13:40:10Z","modified":"2024-08-04T03:08:31.511Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:32:59.105382Z"}],"euvd":[{"id":"EUVD-2021-2358","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).","status":"published","published":"2021-10-29T13:40:10Z","modified":"2024-08-04T03:08:31Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-03T03:24:18.226903Z"}],"ghsa":[{"id":"GHSA-hwhf-64mh-r662","title":"ReDoS vulnerability in parser_apache2","description":"### Impact\nparser_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.\n\n### Patches\nv1.14.2\n\n### Workarounds\nEither of the following:\n\n* Don't use parser_apache2 for parsing logs which cannot guarantee generated by Apache.\n* 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).\n\n### References\n* [CVE-2021-41186](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-41186)\n* [GHSA-hwhf-64mh-r662](https://github.com/fluent/fluentd/security/advisories/GHSA-hwhf-64mh-r662)\n* [GHSL-2021-102](https://securitylab.github.com/advisories/GHSL-2021-102-fluent-fluentd/)\n* https://github.com/fluent/fluentd/blob/master/CHANGELOG.md#v1142\n","status":"published","published":"2021-11-01T19:16:31Z","modified":"2023-05-04T19:33:42Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:36:52.310293Z"}],"nvd":[{"id":"CVE-2021-41186","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).","status":"published","published":"2021-10-29T14:15:07.73Z","modified":"2026-06-17T04:08:03.12Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:N/A:P","level":"medium","assessor":"primary"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:07:00.549994Z"}],"osv":[{"id":"CVE-2021-41186","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).","status":"published","published":"2021-10-29T14:15:07.73Z","modified":"2026-10-20T10:54:57.713193479Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:44:21.249056Z"},{"id":"GHSA-hwhf-64mh-r662","title":"ReDoS vulnerability in parser_apache2","description":"### Impact\nparser_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.\n\n### Patches\nv1.14.2\n\n### Workarounds\nEither of the following:\n\n* Don't use parser_apache2 for parsing logs which cannot guarantee generated by Apache.\n* 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).\n\n### References\n* [CVE-2021-41186](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-41186)\n* [GHSA-hwhf-64mh-r662](https://github.com/fluent/fluentd/security/advisories/GHSA-hwhf-64mh-r662)\n* [GHSL-2021-102](https://securitylab.github.com/advisories/GHSL-2021-102-fluent-fluentd/)\n* https://github.com/fluent/fluentd/blob/master/CHANGELOG.md#v1142\n","status":"published","published":"2021-11-01T19:16:31Z","modified":"2026-07-08T06:28:53.596219161Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T15:46:49.621585Z"},{"id":"BIT-fluentd-2021-41186","title":"ReDoS vulnerability in parser_apache2","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).","status":"published","published":"2024-03-06T10:52:03.183Z","modified":"2026-09-08T08:47:10.569984764Z","updated_at":"2026-11-02T15:28:29.563843Z"},{"id":"openSUSE-SU-2024:11795-1","title":"ruby3.1-rubygem-fluentd-1.14.4-1.1 on GA media","description":"These are all security issues fixed in the ruby3.1-rubygem-fluentd-1.14.4-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2024-06-15T00:00:00Z","modified":"2026-02-04T04:01:10.021958Z","updated_at":"2026-11-02T16:58:35.195147Z"},{"id":"openSUSE-SU-2024:13155-1","title":"ruby3.2-rubygem-fluentd-1.15.3-1.4 on GA media","description":"These are all security issues fixed in the ruby3.2-rubygem-fluentd-1.15.3-1.4 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2024-06-15T00:00:00Z","modified":"2026-02-04T03:28:09.55341Z","updated_at":"2026-11-02T16:58:36.025801Z"},{"id":"openSUSE-SU-2024:14072-1","title":"ruby3.3-rubygem-fluentd-1.17.0-1.1 on GA media","description":"These are all security issues fixed in the ruby3.3-rubygem-fluentd-1.17.0-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2024-06-24T00:00:00Z","modified":"2026-02-04T03:23:40.412564Z","updated_at":"2026-11-02T16:58:36.662953Z"},{"id":"openSUSE-SU-2025:15115-1","title":"ruby3.4-rubygem-fluentd-1.17.1-1.3 on GA media","description":"These are all security issues fixed in the ruby3.4-rubygem-fluentd-1.17.1-1.3 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2025-05-17T00:00:00Z","modified":"2026-02-04T03:05:30.791971Z","updated_at":"2026-11-02T16:58:37.399567Z"},{"id":"openSUSE-SU-2026:10346-1","title":"ruby4.0-rubygem-fluentd-1.17.1-1.5 on GA media","description":"These are all security issues fixed in the ruby4.0-rubygem-fluentd-1.17.1-1.5 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-03-13T00:00:00Z","modified":"2026-03-14T08:44:10.412594Z","updated_at":"2026-11-02T16:58:38.101535Z"}]}}