Code execution or crash via freed object access
Published Nov 15, 2021 · Updated Nov 3, 2025
Use-after-free in the awk applet in BusyBox 1.18 through 1.33.1 allows attackers to crash awk or execute code via a crafted pattern. The handle_special function accesses a freed object while processing the attacker-controlled pattern. Exploitation requires control of awk's first positional argument; default builds include awk, and the bounded result is a process crash or code execution.
Summary
What happened
Use-after-free in the awk applet in BusyBox 1.18 through 1.33.1 allows attackers to crash awk or execute code via a crafted pattern. The handle_special function accesses a freed object while processing the attacker-controlled pattern. Exploitation requires control of awk's first positional argument; default builds include awk, and the bounded result is a process crash or code execution.
The record
- CVE
- CVE-2021-42384
- Published
- Nov 15, 2021
- Updated
- Nov 3, 2025
- Vendor
- BusyBox
- Product
- BusyBox
- Classifications
- CWE-416
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- Nov 15, 2021CVE publishedPublication date reported by the CVE source.
- Nov 3, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=unspecified <1.34.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
Public exploit references
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Technologies
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Your stack
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