Security readout for executives and security teams
Plain-English summary
CVE-2021-42386 is a memory-safety flaw in BusyBox awk. A crafted awk pattern can crash the process and may allow code execution. Business urgency is highest where BusyBox is embedded in appliances, firmware, containers, or Linux systems that process awk input from users or automation.
Executive priority
Treat as high priority for embedded Linux, appliance, and container estates. It is not KEV-listed in the provided data, but memory corruption plus possible code execution justifies prompt inventory and vendor patch tracking.
Technical view
The issue is a use-after-free (CWE-416) in the BusyBox awk applet, specifically the nvalloc function, triggered while processing a crafted awk pattern. The CVSS 3.1 score is 7.2 with high confidentiality, integrity, and availability impact, but the vector lists high privileges required.
Likely exposure
Exposure depends on whether BusyBox awk is present and reachable through local scripts, admin interfaces, APIs, automation pipelines, or vendor firmware. The provided data does not identify exact upstream affected versions, so inventory and vendor-specific advisories matter.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. Public descriptions state denial of service and possible code execution from crafted awk pattern processing. CVSS indicates high privileges are required, reducing broad unauthenticated exposure.
Researcher notes
Evidence is clear on bug class, component, and trigger, but incomplete on exact upstream affected versions and exploit maturity. Avoid assuming all BusyBox deployments are exploitable; validate awk availability, input control, privilege context, and vendor patch status.
Mitigation direction
- Inventory systems, images, appliances, and firmware that include BusyBox awk.
- Update BusyBox through the relevant OS, firmware, or vendor-supported package channel.
- Review Fedora, Debian LTS, NetApp, and product-vendor advisories for affected package status.
- Restrict paths where untrusted users can supply awk patterns to BusyBox awk.
- Prioritize vendor firmware updates for embedded and appliance deployments.
Validation and detection
- Confirm whether BusyBox is installed and whether the awk applet is enabled.
- Map any application or automation path that passes user-controlled patterns to awk.
- Compare installed package or firmware versions with vendor advisory guidance.
- Verify updates in staging before production rollout.
- Monitor logs for abnormal BusyBox awk crashes where awk handles external input.
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-2021-42386 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.