PT-2021-23159 · Fluentd · Fluentd

Ashie

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Published

2021-10-29

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Updated

2026-03-13

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CVE-2021-41186

CVSS v3.1

5.9

Medium

VectorAV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Name of the Vulnerable Software and Affected Versions Fluentd versions 0.14.14 through 1.14.1
Description The parser apache2 plugin in Fluentd 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.
Recommendations For versions 0.14.14 through 1.14.1, either do not use the parser apache2 for parsing logs or put a patched version of parser apache2.rb into the /etc/fluent/plugin directory (or any other directories specified by the environment variable FLUENT PLUGIN or the --plugin option of fluentd). For version 1.14.2 and later, no action is required as this issue is patched.

Exploit

Fix

Resource Exhaustion

Weakness Enumeration

Related Identifiers

BIT-FLUENTD-2021-41186
CVE-2021-41186
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

Affected Products

Fluentd