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ReDoS vulnerability in parser_apache2

Moderate
ashie published GHSA-hwhf-64mh-r662 Oct 29, 2021

Package

bundler fluentd (RubyGems)

Affected versions

>= 0.14.14, <= 1.14.1

Patched versions

1.14.2

Description

Impact

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.

Patches

v1.14.2

Workarounds

Either of the following:

  • Don't use parser_apache2 for parsing logs which cannot guarantee generated by Apache.
  • 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).

References

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVE ID

CVE-2021-41186

Weaknesses

No CWEs