Security readout for executives and security teams
Plain-English summary
BusyBox’s awk utility can mishandle memory when processing a crafted awk pattern. On systems that include the vulnerable applet, an attacker with high privileges could crash the process and may be able to execute code. Business risk is highest for embedded Linux devices, appliances, and distributions where BusyBox is bundled and hard to inventory.
Executive priority
Treat as a high-priority inventory and patching issue for embedded and appliance-heavy environments. Urgency increases where high-privilege users, management interfaces, or automation can pass untrusted data into BusyBox awk.
Technical view
CVE-2021-42381 is a CWE-416 use-after-free in BusyBox awk’s hash_init handling. The CVSS 3.1 score is 7.2, with network attack vector, low complexity, high privileges required, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is likely in Linux distributions, containers, firmware, NAS, network devices, and embedded products that ship BusyBox with the awk applet enabled. Risk is lower where BusyBox awk is absent, inaccessible, or never processes attacker-influenced awk patterns.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. The vulnerability requires processing a crafted awk pattern, and CVSS indicates high privileges are required. Sources describe denial of service and possible code execution, but do not provide confirmed exploitation evidence.
Researcher notes
Affected versions are unspecified in the source bundle, so version scoping must come from vendor advisories and package metadata. Do not assume all BusyBox deployments are exploitable; validate awk applet presence, privilege path, and input control.
Mitigation direction
- Inventory systems, firmware, containers, and appliances that include BusyBox awk.
- Apply BusyBox updates from operating system, firmware, or appliance vendors.
- Review Fedora, Debian, NetApp, and other vendor guidance for affected packages.
- Remove or disable BusyBox awk where it is not operationally required.
- Restrict high-privilege access paths that can invoke awk with untrusted patterns.
Validation and detection
- Confirm whether BusyBox is installed and whether the awk applet is enabled.
- Map BusyBox package or firmware versions to vendor advisories.
- Use SBOM or firmware analysis to find embedded BusyBox copies.
- Verify patched packages or firmware are deployed after remediation.
- Review scripts and services for attacker-influenced awk pattern handling.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-416: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-42381 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.2 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H1.25.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.2HighVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://jfrog.com/blog/unboxing-busybox-14-new-vulnerabilities-uncovered-by-claroty-and-jfrog/CVE reference
- FEDORA-2021-5a95823596CVE reference · vendor-advisory
- FEDORA-2021-c52c0fe490CVE reference · vendor-advisory
- https://security.netapp.com/advisory/ntap-20211223-0002/CVE reference
- https://claroty.com/team82/research/unboxing-busybox-14-vulnerabilities-uncovered-by-claroty-jfrogCVE reference
- https://lists.debian.org/debian-lts-announce/2025/01/msg00012.htmlCVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.