CVE-2021-41186

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).

Category

5.9
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.48%
Third-Party Advisory github.com Third-Party Advisory github.com
Affected: fluent fluentd
Published at:
Updated at:

References

Link Tags
https://github.com/fluent/fluentd/security/advisories/GHSA-hwhf-64mh-r662 third party advisory
https://github.com/fluent/fluentd/blob/master/CHANGELOG.md#v1142 third party advisory release notes
https://github.com/github/securitylab-vulnerabilities/blob/52dc4a2a828c6dc24231967c2937ad92038184a9/vendor_reports/GHSL-2021-102-fluent-fluentd.md broken link

Frequently Asked Questions

What is the severity of CVE-2021-41186?
CVE-2021-41186 has been scored as a medium severity vulnerability.
How to fix CVE-2021-41186?
To fix CVE-2021-41186, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-41186 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-41186 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-41186?
CVE-2021-41186 affects fluent fluentd.
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