FedoraOperating system · Fedoraproject
CVE-2021-42378
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 getvar_i 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 exists in BusyBox's awk applet within the getvar_i function. When processing a specially crafted awk pattern, memory is freed but subsequently accessed, leading to potential denial of service and possible code execution. The CVSS 7.2 indicates high severity due to the memory corruption nature.
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>= 1.16.0, <= 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 installed BusyBox versionRun `busybox --version` to retrieve the installed BusyBox version numberAffected if Version is between 1.16.0 and 1.33.1 inclusive
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Verify awk applet is availableRun `busybox --list | grep awk` or `which awk` to confirm the awk applet is present in the BusyBox binaryAffected if The awk command is available and linked to BusyBox
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Confirm awk functionality is in useCheck for any scripts, cron jobs, or applications that invoke the awk command on the systemAffected if Awk is being executed, especially on untrusted input
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Identify the BusyBox binary locationRun `file $(which busybox)` or check the binary directly to confirm it is the vulnerable versionAffected if The binary is a standard BusyBox build containing the vulnerable awk code
A system is affected if it runs BusyBox version 1.16.0 through 1.33.1 with the awk applet enabled and processes awk 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-2021-42378. If updates are not immediately feasible, avoid processing untrusted awk patterns and consider restricting access to systems where BusyBox awk is used.
BusyBox 1.34.0 or later (or the latest available version in your distribution's repository)
- 1. Identify the current BusyBox version by running: busybox --version
- 2. For Fedora systems (33, 34), run: sudo dnf update busybox
- 3. Verify the update was successful by checking the new version: busybox --version
- 4. Ensure the updated version is 1.34.0 or later which contains the fix for CVE-2021-42378
- 5. Test that critical BusyBox-dependent functionality works as expected after the update
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Fedora
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 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 $3,328.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-42378 — 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-2021-42378 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
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