FedoraOperating system · Fedoraproject
CVE-2021-42379
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 next_input_file 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 · moderate confidenceA use-after-free vulnerability in BusyBox's awk applet in the next_input_file function allows attackers to cause denial of service and potentially achieve code execution by processing a specially crafted awk pattern.
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>= 1.18.0, <= 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.
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Check BusyBox versionRun `busybox --version` or `/bin/busybox --version` and compare the output to the affected range (1.18.0 through 1.33.1 inclusive)Affected if The version falls within >= 1.18.0 and <= 1.33.1
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Verify awk applet is availableRun `busybox --help | grep -i awk` or check if the awk binary/symlink exists (e.g., `ls -l /bin/awk` or `/usr/bin/awk` pointing to busybox)Affected if The awk applet is present and enabled in the BusyBox build
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Check for direct awk usageRun `which awk` and `file $(which awk)` to confirm awk is provided by BusyBox, then examine running processes or scripts that invoke awkAffected if awk commands are being executed using the BusyBox implementation
You are affected if BusyBox version is between 1.18.0 and 1.33.1 AND the awk applet is enabled and actively used in your environment.
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 patched version that addresses CVE-2021-42379, or disable the awk applet if not required in the deployment.
Busybox 1.34.0 or later (or equivalent patched version from your Linux distribution)
- Check the current Busybox version by running: busybox --version
- For Fedora systems, update Busybox using: dnf update busybox
- For other systems, obtain and install Busybox version 1.34.0 or later from the official Busybox website or distribution repositories
- Verify the update was successful by running: busybox --version
- Ensure the new version is 1.34.0 or higher to confirm the vulnerability is patched
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
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-42379 — 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-2021-42379 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
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- 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
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