CVE-2021-41186 Security Vulnerability & Exploit Details

CVE-2021-41186
Vulnerability Scoring

5.9

/10

Significant Risk

Security assessments indicate that CVE-2021-41186 presents a notable risk, potentially requiring prompt mitigation.

Attack Complexity Details

Attack Complexity: High
Exploits require significant effort and special conditions.
Attack Vector: Network
Vulnerability is exploitable over a network without physical access.
Privileges Required: None
No privileges are required for exploitation.
Scope: Unchanged
Exploit remains within the originally vulnerable component.
User Interaction: None
No user interaction is necessary for exploitation.

CVE-2021-41186 Details

Status: Modified

Last updated: 🕕 21 Nov 2024, 06:25 UTC
Originally published on: 🕑 29 Oct 2021, 14:15 UTC

Time between publication and last update: 1118 days

CVSS Release: version 3

CVSS3 Source

security-advisories@github.com

CVSS3 Type

Secondary

CVSS3 Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVE-2021-41186 Vulnerability Summary

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).

Assessing the Risk of CVE-2021-41186

Access Complexity Graph

The exploitability of CVE-2021-41186 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2021-41186

CVE-2021-41186 presents a challenge to exploit due to its high attack complexity, but the absence of privilege requirements still makes it a viable target for skilled attackers. A thorough security review is advised.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2021-41186, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2021-41186, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

Confidentiality: None
CVE-2021-41186 has no significant impact on data confidentiality.
Integrity: None
CVE-2021-41186 poses no threat to data integrity.
Availability: High
CVE-2021-41186 can disrupt system operations, potentially causing complete denial of service (DoS).

Exploit Prediction Scoring System (EPSS)

The EPSS score estimates the probability that this vulnerability will be exploited in the near future.

EPSS Score: 0.252% (probability of exploit)

EPSS Percentile: 64.91% (lower percentile = lower relative risk)
This vulnerability is less risky than approximately 35.09% of others.

CVE-2021-41186 References

External References

CWE Common Weakness Enumeration

CWE-400

CAPEC Common Attack Pattern Enumeration and Classification

XML Ping of the Death CAPEC-147 An attacker initiates a resource depletion attack where a large number of small XML messages are delivered at a sufficiently rapid rate to cause a denial of service or crash of the target. Transactions such as repetitive SOAP transactions can deplete resources faster than a simple flooding attack because of the additional resources used by the SOAP protocol and the resources necessary to process SOAP messages. The transactions used are immaterial as long as they cause resource utilization on the target. In other words, this is a normal flooding attack augmented by using messages that will require extra processing on the target.
Sustained Client Engagement CAPEC-227 An adversary attempts to deny legitimate users access to a resource by continually engaging a specific resource in an attempt to keep the resource tied up as long as possible. The adversary's primary goal is not to crash or flood the target, which would alert defenders; rather it is to repeatedly perform actions or abuse algorithmic flaws such that a given resource is tied up and not available to a legitimate user. By carefully crafting a requests that keep the resource engaged through what is seemingly benign requests, legitimate users are limited or completely denied access to the resource.
Regular Expression Exponential Blowup CAPEC-492 An adversary may execute an attack on a program that uses a poor Regular Expression(Regex) implementation by choosing input that results in an extreme situation for the Regex. A typical extreme situation operates at exponential time compared to the input size. This is due to most implementations using a Nondeterministic Finite Automaton(NFA) state machine to be built by the Regex algorithm since NFA allows backtracking and thus more complex regular expressions.

Vulnerable Configurations

cpe:2.3:a:fluentd:fluentd:0.14.14:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.14:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.15:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.15:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.16:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.16:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.17:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.17:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.18:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.18:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.19:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.19:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.20:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.20:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.20:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.20:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.21:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.21:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.22:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.22:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.22:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.22:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.22:rc2:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.22:rc2:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.23:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.23:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.23:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.23:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.24:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.24:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.25:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:0.14.25:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.0.0:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.0.0:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.0.0:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.0.0:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.0.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.0.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.0.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.0.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.1.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.1.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.1.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.1.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.1.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.1.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.1.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.1.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.4:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.4:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.4:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.4:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.5:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.5:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.5:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.5:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.6:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.2.6:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.3.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.3.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.3.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.3.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.3.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.3.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.3.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.3.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.4.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.4.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.4.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.4.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.4.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.4.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.5.0:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.5.0:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.5.0:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.5.0:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.5.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.5.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.5.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.5.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.6.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.6.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.6.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.6.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.6.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.6.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.6.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.6.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.7.0:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.7.0:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.7.0:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.7.0:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.7.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.7.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.7.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.7.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.7.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.7.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.7.4:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.7.4:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.8.0:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.8.0:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.8.0:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.8.0:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.8.0:rc2:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.8.0:rc2:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.8.0:rc3:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.8.0:rc3:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.8.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.8.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.9.0:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.9.0:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.9.0:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.9.0:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.9.0:rc2:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.9.0:rc2:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.9.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.9.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.9.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.9.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.9.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.9.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.10.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.10.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.10.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.10.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.10.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.10.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.10.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.10.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.10.4:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.10.4:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.11.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.11.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.11.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.11.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.11.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.11.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.11.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.11.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.11.4:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.11.4:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.11.5:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.11.5:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.0:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.0:-:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.0:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.0:rc1:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.0:rc2:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.0:rc2:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.4:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.12.4:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.13.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.13.0:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.13.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.13.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.13.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.13.2:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.13.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.13.3:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.14.1:*:*:*:*:*:*:*
cpe:2.3:a:fluentd:fluentd:1.14.1:*:*:*:*:*:*:*

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CVE-2021-41186 Vulnerability Scoring