CVE-2021-42383Network attack vector

Process crash or code execution via freed memory

Published Nov 15, 2021 · Updated Apr 23, 2025

Use-after-free in BusyBox awk before 1.34.0 allows attackers to crash its process or possibly execute code through a crafted pattern. The evaluate function accesses freed memory while processing an attacker-controlled awk program. Exploitation requires control of the awk program argument; a crash normally terminates only the forked applet process.

CVSS severity7.2
High
EPSS probability2.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in BusyBox awk before 1.34.0 allows attackers to crash its process or possibly execute code through a crafted pattern. The evaluate function accesses freed memory while processing an attacker-controlled awk program. Exploitation requires control of the awk program argument; a crash normally terminates only the forked applet process.

The record

CVE
CVE-2021-42383
Published
Nov 15, 2021
Updated
Apr 23, 2025
Vendor
BusyBox
Product
BusyBox
Classifications
CWE-416
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Nov 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 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.

  1. Affected versionversion=unspecified <1.34.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

BusyBox · BusyBoxversion=unspecified <1.34.0

Published CVSS scores

7.2CISA-ADPCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P
7.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free

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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