Service crash via crafted awk pattern
Published Nov 15, 2021 · Updated Nov 3, 2025
A use-after-free in BusyBox awk before 1.34.0 allows attackers to crash the applet by supplying a crafted awk pattern. The getvar_i function accesses freed memory while processing the attacker-controlled pattern. Exploitation requires the pattern to reach awk as its first argument; researchers demonstrated crash potential but did not develop code execution.
Summary
What happened
A use-after-free in BusyBox awk before 1.34.0 allows attackers to crash the applet by supplying a crafted awk pattern. The getvar_i function accesses freed memory while processing the attacker-controlled pattern. Exploitation requires the pattern to reach awk as its first argument; researchers demonstrated crash potential but did not develop code execution.
The record
- CVE
- CVE-2021-42378
- Published
- Nov 15, 2021
- Updated
- Nov 3, 2025
- Vendor
- BusyBox
- Product
- BusyBox
- Classifications
- CWE-416, T1059
- 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=unspecified <1.34.0
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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