FedoraOperating system · Fedoraproject
CVE-2021-42383
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA use-after-free in Busybox's awk applet leads to denial of service and possibly code execution when processing a crafted awk pattern in the evaluate function
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA use-after-free vulnerability exists in Busybox's awk applet within the evaluate function. When processing a specially crafted awk pattern, the memory allocated for a variable is freed but subsequently accessed, leading to denial of service and potential code execution.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
FedoraOperating system
= 33= 34= 1.33.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Check if Busybox is installedRun 'busybox --version' or 'busybox' alone to see the installed Busybox version and confirm it's present on the systemAffected if Busybox is not installed or the command fails - not applicable to this CVE
-
Identify the Busybox versionExamine the output from 'busybox --version' to determine the exact version number (e.g., 1.33.1)Affected if The version is 1.33.1 specifically, which matches the affected version range
-
Verify the awk applet is availableRun 'busybox awk --help' or check if 'awk' is a symlink to busybox (ls -la $(which awk))Affected if The awk applet is present and can be invoked through Busybox, meaning the vulnerable code path exists in this environment
-
Confirm awk functionality is accessibleTry executing 'busybox awk' or simply 'awk' to verify the applet is enabled in this Busybox buildAffected if The awk command executes without error, indicating the vulnerable applet is enabled and could process malicious input
You are affected if Busybox version 1.33.1 is installed AND the awk applet is available/enabled in your Busybox build, as the use-after-free flaw exists specifically in the awk evaluate function when processing crafted patterns.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpdate Busybox to a version containing the fix for CVE-2021-42383, or disable the awk applet if not required in production environments.
Busybox 1.33.2 or later / Fedora updated packages
- 1. Identify the Busybox version currently installed: `busybox --version`
- 2. For Fedora 33 and 34 systems, apply the latest available security updates via: `sudo dnf update busybox`
- 3. Verify the updated version is at least 1.33.2 or later which contains the fix for CVE-2021-42383
- 4. Test the awk functionality to ensure normal operation: `echo '1' | busybox awk '{print $1}'`
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Fedora
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-42383 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-42383 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data