What is CVE-2021-41186?
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).
The record classifies CVE-2021-41186 under weakness class CWE-400. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 1820 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 5.9 — MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS (FIRST)
- 2.2% probability of exploitation in the next 30 days, higher than 82.1% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 6.2/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2021-10-29, last modified 2024-08-04
Is CVE-2021-41186 being exploited?
It currently carries a trending score of 26 in the Threadlinqs vulnerability feed.
Affected products and versions
- fluent: fluentd
How to fix CVE-2021-41186
No vendor patch reference has been recorded for CVE-2021-41186 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2021-41186
1 tracked threat in the Threadlinqs corpus references CVE-2021-41186, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, FIRST EPSS. Last verified by Threadlinqs on .