What is the CVSS score of CVE-2021-42375?

CVE-2021-42375 has a CVSS 3.1 base score of 5.5 (Medium). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.4%.

Busybox CVE-2021-42375

MEDIUM

Improper Handling of Invalid Use of Special Elements (CWE-159)

2021-11-15 reefs@jfrog.com

Denial Of Service Fedora H300s Firmware H410s Firmware H500s Firmware H700s Firmware Hci Management Node Solidfire Busybox H300E Firmware H500E Firmware H700E Firmware Cloud Backup Netapp Fedoraproject

5.5

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-159 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V1 - Encoding and Sanitization Special element handling
Impact	CVSS score of 5.5 (MEDIUM). Attack characteristics: local attack vector, low complexity, low privileges required, no user interaction not required.
Exploit ScenarioDerived	Successful exploitation could compromise the medium-severity affected system.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

No patch listed yet 0.4% exploitation probability (EPSS)

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AnalysisAI

An incorrect handling of a special element in Busybox's ash applet leads to denial of service when processing a crafted shell command, due to the shell mistaking specific characters for reserved. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-159. An incorrect handling of a special element in Busybox's ash applet leads to denial of service when processing a crafted shell command, due to the shell mistaking specific characters for reserved characters. This may be used for DoS under rare conditions of filtered command input. Affected products include: Busybox, Fedoraproject Fedora, Netapp Cloud Backup, Netapp Hci Management Node, Netapp Solidfire.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 5.5 MEDIUM

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

DescriptionNVD

An incorrect handling of a special element in Busybox's ash applet leads to denial of service when processing a crafted shell command, due to the shell mistaking specific characters for reserved characters. This may be used for DoS under rare conditions of filtered command input.

Threat Intelligence Overview

EPSS Score

0.4%

Top 70% exploitable

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity MEDIUM

CISA KEV No

Public POC No

EPSS 0.4%

Patch available No

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Defer

Exploitation· derived

None

System Exposure· derived

Small

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +28

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)NVD

cpe:2.3:a:busybox:busybox:1.33.1:*:*:*:*:*:*:*

cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*

cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*

cpe:2.3:a:netapp:hci_management_node:-:*:*:*:*:*:*:*

cpe:2.3:a:netapp:solidfire:-:*:*:*:*:*:*:*

cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*

cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*

cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:*

cpe:2.3:o:netapp:h300e_firmware:-:*:*:*:*:*:*:*

cpe:2.3:o:netapp:h500e_firmware:-:*:*:*:*:*:*:*

cpe:2.3:o:netapp:h700e_firmware:-:*:*:*:*:*:*:*

cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:*

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9.8 Nov 15

An attacker-controlled pointer free in Busybox's hush applet leads to denial of service and possible code execution when

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9.8 Jun 26

BusyBox project BusyBox wget version prior to commit 8e2174e9bd836e53c8b9c6e00d1bc6e2a718686e contains a Buffer Overflow

CVE-2023-42366 MEDIUM This Month POC

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A heap-buffer-overflow was discovered in BusyBox v.1.36.1 in the next_token function at awk.c:1159. Rated medium severit

Same weakness CWE-159 – Improper Handling of Invalid Use of Special Elements

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7.5

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5.3

Same technique Denial Of Service

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CVE-2015-5119 CRITICAL POC

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CVE-2011-2462 CRITICAL POC

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CVE-2011-0611 HIGH POC

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CVE-2012-1889 HIGH POC

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CVE-2012-0507 CRITICAL POC

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CVE-2014-1761 HIGH POC

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CVE-2015-5122 CRITICAL POC

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CVE-2011-0609 HIGH POC

7.8

References

Advisories & patches

REF https://claroty.com/team82/research/unboxing-busybox-14-vulnerabilities-uncovered-by-claroty-jfrog REF https://jfrog.com/blog/unboxing-busybox-14-new-vulnerabilities-uncovered-by-claroty-and-jfrog/ REF https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6T2TURBYYJGBMQTTN2DSOAIQGP7WCPGV/ REF https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UQXGOGWBIYWOIVXJVRKHZR34UMEHQBXS/ REF https://security.netapp.com/advisory/ntap-20211223-0002/

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