An incorrect handling of a special element in Busybox's ash applet leads to denial of…
Priority LOW 25CWE-159Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00409 35th percentileScored 2026-11-07
Fix Fixed busybox (busybox): 1.34.0
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| busybox | busybox | before 1.34.0 | 1.34.0 | Patch available | CNA |
- busybox Vendorbusybox Affected before 1.34.0 Fixed in 1.34.0 Patch available CNA
CPE configurations NVD · 20
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:busybox:busybox:1.33.1:*:*:*:*:*:*:* | 1.33.1 | Vulnerable | busybox |
| cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* | 33 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* | 34 | Vulnerable | Fedoraproject |
| cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:a:netapp:hci_management_node:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:a:netapp:solidfire:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:h300s:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
| cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:h500s:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
- cpe:2.3:a:busybox:busybox:1.33.1:*:*:*:*:*:*:* Versions 1.33.1 Vulnerable ·busybox
- cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* Versions 33 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
- cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:a:netapp:hci_management_node:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:a:netapp:solidfire:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:h300s:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
- cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:h500s:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
Show 10 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:h700s:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
| cpe:2.3:o:netapp:h300e_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:h300e:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
| cpe:2.3:o:netapp:h500e_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:h500e:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
| cpe:2.3:o:netapp:h700e_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:h700e:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
| cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:h410s:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
- cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:h700s:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
- cpe:2.3:o:netapp:h300e_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:h300e:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
- cpe:2.3:o:netapp:h500e_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:h500e:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
- cpe:2.3:o:netapp:h700e_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:h700e:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
- cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:h410s:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
Remediation
- Fix · CNA busybox (busybox) Fixed in 1.34.0
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
busybox — FEDORA-2021-c52c0fe490
14 records Highest priority Priority MEDIUM 2 MEDIUM, 12 LOW
Other records, highest priority first
- TI-2021-18788 Out-of-bounds read in busyboxPriority MEDIUM 57
- TI-2021-18791 An attacker-controlled pointer free in Busybox's hush applet leads to denial of service…Priority MEDIUM 48
- TI-2021-18800 Use after free in busyboxPriority LOW 39
- Advisory ·
busybox — FEDORA-2021-5a95823596
14 records Highest priority Priority MEDIUM 2 MEDIUM, 12 LOW
Other records, highest priority first
- TI-2021-18788 Out-of-bounds read in busyboxPriority MEDIUM 57
- TI-2021-18791 An attacker-controlled pointer free in Busybox's hush applet leads to denial of service…Priority MEDIUM 48
- TI-2021-18800 Use after free in busyboxPriority LOW 39
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 1 product
- Red Hat Enterprise Linux 6
Timeline
- 2026-10-02 Threatist record created from CVE-2021-42375
- 2026-10-03 Alias added: GHSA-h7xx-2pfg-qqhm
References
Advisory 4
More Busybox vulnerabilities
- TI-2016-05394 The recv_and_process_client_pkt function in networking/ntpd.c in busybox allows remote… CVSS 3.1HIGH 7.5
- TI-2018-15900 Busybox contains a Missing SSL certificate validation vulnerability in The "busybox wget"… CVSS 3.1HIGH 8.1
- TI-2018-15917 BusyBox project BusyBox wget version prior to commit… CVSS 3.1CRITICAL 9.8
- TI-2016-01959 Heap-based buffer overflow in the DHCP client (udhcpc) in BusyBox before 1.25.0 allows… CVSS 3.1CRITICAL 9.8
- TI-2025-37846 BusyBox wget thru 1.3.7 accepted raw CR (0x0D)/LF (0x0A) and other C0 control bytes in… CVSS 3.1MEDIUM 6.5
- TI-2023-22583 A use-after-free vulnerability in BusyBox v.1.36.1 allows attackers to cause a denial of… CVSS 3.1MEDIUM 5.5
Sources
- CVE-2021-42375 · CVE Program
- CVE-2021-42375 · NVD
- FIRST EPSS
- GHSA-h7xx-2pfg-qqhm · GitHub Advisory Database · CC BY 4.0
- CVE-2021-42375 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences