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CVE-2021-41186

5.9 · MEDIUM

Fluentd collects events from various data sources and writes them to files to help unify logging infrastructure.

Published Oct 29, 2021CWE-400EPSS 2.21%

Overview

CVE-2021-41186 is a medium-severity vulnerability. It was published on October 29, 2021 and has a CVSS 3.1 base score of 5.9 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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).

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/fluent/fluentd/blob/master/CHANGELOG.md#v1142GitHubgithub.com/fluent/fluentd/security/advisories/GHSA-hwhf-64mh-r662GitHubgithub.com/github/securitylab-vulnerabilities/blob/52dc4a2a828c6dc24231967c2937ad92038184a9/vendor_reports/GHSL-2021-102-fluent-fluentd.mdGitHubgithub.com/fluent/fluentd/blob/master/CHANGELOG.md#v1142GitHubgithub.com/fluent/fluentd/security/advisories/GHSA-hwhf-64mh-r662GitHubgithub.com/github/securitylab-vulnerabilities/blob/52dc4a2a828c6dc24231967c2937ad92038184a9/vendor_reports/GHSL-2021-102-fluent-fluentd.md

How CyberStrike helps

Frequently asked questions

What is CVE-2021-41186?

CVE-2021-41186 is a medium-severity vulnerability. It was published on October 29, 2021 and has a CVSS 3.1 base score of 5.9 (MEDIUM).

How severe is CVE-2021-41186?

This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-41186?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-41186?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-41186 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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