CVE-2021-42373Public exploit

Applet crash via missing manual page argument

Published Nov 15, 2021 · Updated Aug 4, 2024

NULL pointer dereference in the man applet in BusyBox 1.33.0 through 1.33.1 allows local users to crash the applet via a lone section argument. man_main treats the sole argument as a section, advances argv past it, then dereferences the resulting null page pointer. The man applet must be compiled in and receive attacker-controlled parameters; the crash is confined to its forked process rather than the host.

CVSS severity5.5
Medium
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in the man applet in BusyBox 1.33.0 through 1.33.1 allows local users to crash the applet via a lone section argument. man_main treats the sole argument as a section, advances argv past it, then dereferences the resulting null page pointer. The man applet must be compiled in and receive attacker-controlled parameters; the crash is confined to its forked process rather than the host.

The record

CVE
CVE-2021-42373
Published
Nov 15, 2021
Updated
Aug 4, 2024
Vendor
BusyBox
Product
BusyBox
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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 vectorlocal
Required privilegesauthenticated

What is affected?

BusyBox · BusyBoxversion=unspecified <1.34.0

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:P

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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