CVE-2021-41186 is a medium-severity uncontrolled resource consumption vulnerability in fluentd (rubygems), affecting versions >= 0.14.14, < 1.14.2. It is fixed in 1.14.2.
Impact parserapache2 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. Patches v1.14.2 Workarounds Either of the following: Don't use parserapache2 for parsing logs which cannot guarantee generated by Apache. Put patched version of parserapache2.rb into /etc/fluent/plugin directory (or any other directories specified by the environment variable FLUENTPLUGIN or --plugin option of fluentd). References CVE-2021-41186 GHSA-hwhf-64mh-r662 GHSL-2021-102 https://github.com/fluent/fluentd/blob/master/CHANGELOG.md#v1142
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
CVE-2021-41186 has a CVSS score of 5.9 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
A fixed version is available (1.14.2). Upgrading removes the vulnerable code path.
rubygems
fluentd (>= 0.14.14, < 1.14.2)fluentd → 1.14.2 (rubygems)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter instead of chasing every advisory.
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Already deployed Kodem? See CVE-2021-41186 in your environment →Upgrade fluentd to 1.14.2 or later to resolve this vulnerability.
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CVE-2021-41186 is a medium-severity uncontrolled resource consumption vulnerability in fluentd (rubygems), affecting versions >= 0.14.14, < 1.14.2. It is fixed in 1.14.2. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
CVE-2021-41186 has a CVSS score of 5.9 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
fluentd (rubygems) versions >= 0.14.14, < 1.14.2 is affected.
Yes. CVE-2021-41186 is fixed in 1.14.2. Upgrade to this version or later.
Whether CVE-2021-41186 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade fluentd to 1.14.2 or later.