Security readout for executives and security teams
Plain-English summary
BusyBox includes a flaw in its awk applet that can crash affected systems and may allow code execution when crafted awk input is processed. BusyBox is common in compact Linux environments, so exposure may hide inside appliances, firmware, containers, and distributions rather than obvious standalone software.
Executive priority
Treat this as a high-priority hygiene and embedded-software exposure issue, not confirmed emergency exploitation. Focus first on internet-managed appliances, OT or IoT assets, and platforms where BusyBox is bundled and patch visibility is weak.
Technical view
CVE-2021-42378 is a CWE-416 use-after-free in BusyBox awk, specifically the getvar_i function, triggered while processing a crafted awk pattern. 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
Systems are exposed if they ship BusyBox with the awk applet and allow crafted awk patterns to be processed. The bundle names BusyBox generally, with advisories from Fedora, Debian LTS, and NetApp, but does not provide exact upstream affected versions.
Exploitation context
The provided data does not show CISA KEV listing or active exploitation. The CVSS vector indicates high privileges are required, so business risk depends on where BusyBox awk is reachable, especially in managed appliances, embedded environments, or privileged automation paths.
Researcher notes
Evidence is limited on exact affected version ranges and fixed upstream versions in the provided bundle. Validation should avoid exploit reproduction and focus on component discovery, advisory mapping, and whether privileged workflows can feed crafted awk patterns to BusyBox awk.
Mitigation direction
- Inventory BusyBox versions and confirm whether the awk applet is present.
- Apply vendor or distribution BusyBox updates where available.
- Check Fedora, Debian LTS, NetApp, and device vendor advisories for applicable fixes.
- Restrict untrusted users or automation from supplying awk patterns to BusyBox awk.
- Prioritize firmware and appliance updates where BusyBox is bundled indirectly.
Validation and detection
- Search SBOMs, firmware manifests, and images for BusyBox packages.
- Confirm whether BusyBox awk is installed or symlinked on target systems.
- Map systems to vendor advisories before assuming patch coverage.
- Review scripts, APIs, and jobs that pass user-controlled input into awk.
- Verify updated packages or firmware are deployed after remediation.
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-2021-42378 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.