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NVD / CVE Program· CNA JFROG

CVE-2021-42375: An incorrect handling of a special element in Busybox's ash applet leads to denial of service when processing a crafted shell command, due t

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.40% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: busybox (Alpine:v3.13) 1.32.1-r7; busybox (Alpine:v3.14) 1.33.1-r5; busybox (Alpine:v3.15) 1.34.0-r0.

Low priority for now. Upgrade to busybox (Alpine:v3.13) 1.32.1-r7; busybox (Alpine:v3.14) 1.33.1-r5; busybox (Alpine:v3.15) 1.34.0-r0 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Nov 15, 2021
Updated
Jun 17, 2026
EPSS
0.4% · 35th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-42375

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
busyboxbusybox
fedoraprojectfedora
netappcloud backup
netapphci management node
netappsolidfire
netapph300s firmware
netapph300s
netapph500s firmware
netapph500s
netapph700s firmware
netapph700s
netapph300e firmware

and 7 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • busybox busybox1.33.1
  • fedoraproject fedora33
  • fedoraproject fedora34
  • netapp cloud backupall versions
  • netapp h300e firmwareall versions
  • netapp h300s firmwareall versions
  • netapp h410s firmwareall versions
  • netapp h500e firmwareall versions
  • netapp h500s firmwareall versions
  • netapp h700e firmwareall versions
  • netapp h700s firmwareall versions
  • netapp hci management nodeall versions
  • netapp solidfireall versions

Versions reported by the vendor

Affected version ranges reported by the assigning authority (JFROG). Independent of NVD's CPE analysis and usually ahead of it.

  • busybox busybox

    • unspecified and later · before 1.34.0affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.13busyboxbefore 1.32.1-r71.32.1-r7
Alpine:v3.14busyboxbefore 1.33.1-r51.33.1-r5
Alpine:v3.15busyboxbefore 1.34.0-r01.34.0-r0
Debian:12busyboxbefore 1:1.35.0-11:1.35.0-1
openSUSE:Leap 15.3busyboxbefore 1.34.1-4.9.11.34.1-4.9.1
openSUSE:Leap 15.3virtualboxbefore 6.1.34-lp153.2.27.26.1.34-lp153.2.27.2
openSUSE:Leap 15.3virtualbox-kmpbefore 6.1.34-lp153.2.27.16.1.34-lp153.2.27.1
openSUSE:Leap 15.4busyboxbefore 1.35.0-150400.3.3.11.35.0-150400.3.3.1
SUSE:Linux Enterprise Module for Basesystem 15 SP3busyboxbefore 1.34.1-4.9.11.34.1-4.9.1
SUSE:Linux Enterprise Module for Basesystem 15 SP4busyboxbefore 1.35.0-150400.3.3.11.35.0-150400.3.3.1
SUSE:OpenStack Cloud 9busyboxbefore 1.35.0-4.3.11.35.0-4.3.1

Same product

busybox: all records

Other highest-scoring records for the same primary product.

  • CVE-2018-1000517BusyBox project BusyBox wget version prior to commit 8e2174e9bd836e53c8b9c6e00d1bc6e2a718686e contains a Buffer Overflow vulnerability in Bu
    49Plan
  • CVE-2016-2148Heap-based buffer overflow in the DHCP client (udhcpc) in BusyBox before 1.25.0 allows remote attackers to have unspecified impact via vecto
    47Plan
  • CVE-2022-48174There is a stack overflow vulnerability in ash.c:6030 in busybox before 1.35.
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2021-42373Nov 15, 2021 · A NULL pointer dereference in Busybox's man applet leads to denial of service when a section name is supplied but no page argument is given
    22Monitor
  • ← EarlierCVE-2021-42374Nov 15, 2021 · An out-of-bounds heap read in Busybox's unlzma applet leads to information leak and denial of service when crafted LZMA-compressed input is
    21Monitor
  • Later →CVE-2021-42376Nov 15, 2021 · A NULL pointer dereference in Busybox's hush applet leads to denial of service when processing a crafted shell command, due to missing valid
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:busybox1.32.1-r7 · Alpine:v3.13Package registry (OSV)
debian:busybox1:1.35.0-1 · Debian:12Package registry (OSV)
opensuse:busybox1.35.0-150400.3.3.1 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:virtualbox6.1.34-lp153.2.27.2 · openSUSE:Leap 15.3Package registry (OSV)
opensuse:virtualbox-kmp6.1.34-lp153.2.27.1 · openSUSE:Leap 15.3Package registry (OSV)
suse:busybox1.34.1-4.9.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP3Package registry (OSV)
suse:busybox1.35.0-150400.3.3.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP4Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-159 · Improper Handling of Invalid Use of Special Elements

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records