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).
How to fix CVE-2021-41186
To remediate CVE-2021-41186, upgrade the affected package to a fixed version below.
- —upgrade to 1.14.2 or later
Is CVE-2021-41186 being exploited?
Low — EPSS is 2.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 0.14.14, < 1.14.2
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM5.9 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H |