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CVE-2021-42377

31
FAUCET Score

CVE-2021-42377 is a critical vulnerability affecting Busybox, Fedora Project, and NetApp products, specifically within Busybox's hush applet. It involves an attacker-controlled pointer free that can lead to denial of service and potential remote code execution when processing a specially crafted shell command containing "&&&". With a CVSS score of 9.8 (Critical), this vulnerability has a network attack vector, low attack complexity, and high impacts on confidentiality, integrity, and availability. While there is no known active exploitation, public exploit code, or inclusion in CISA's KEV catalog, the vulnerability has garnered some community discussion and media coverage, indicating awareness.

Impacted Technologies

VendorProductVersion(s)CPE
1.33.0CPE matchmatch criteria
cpe:2.3:a:busybox:busybox:1.33.0:*:*:*:*:*:*:*
1.33.1CPE matchmatch criteria
cpe:2.3:a:busybox:busybox:1.33.1:*:*:*:*:*:*:*
33CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.38%
Probability of exploitation in next 30 days
EPSS Percentile
87.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0338 is in the 80th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Advisories (1)

redhatCVE-2021-42377Moderate

busybox: an attacker-controlled pointer free in hush applet leads to denial of service and possible code execution when processing a crafted shell command

Nov 9, 2021

References

claroty.com / team82/research/unboxing-busybox-14-vulnerabilities-uncovered-by-claroty-jfrog
jfrog.com / blog/unboxing-busybox-14-new-vulnerabilities-uncovered-by-claroty-and-jfrog
Third Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/6T2TURBYYJGBMQTTN2DSOAIQGP7WCPGV
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/UQXGOGWBIYWOIVXJVRKHZR34UMEHQBXS
security.netapp.com / advisory/ntap-20211223-0002
Third Party Advisory