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Fencer Vulns
low 3.3

CVE-2021-4217 json

A flaw was found in unzip.

published 2022-08-24 4 y ago modified 2026-11-02 6 d ago also EUVD-2021-34075

cvss
3.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits
0
none known

Summary

A flaw was found in unzip. The vulnerability occurs due to improper handling of Unicode strings, which can lead to a null pointer dereference. This flaw allows an attacker to input a specially crafted zip file, leading to a crash or code execution.

Patch / fix

  • unzip Ubuntu 18.04 LTS 6.0-21ubuntu1.2
  • unzip Ubuntu 20.04 LTS 6.0-25ubuntu1.1
  • unzip Ubuntu 22.04 LTS 6.0-26ubuntu3.1
  • unzip Ubuntu 24.04 LTS 6.0-28ubuntu4.1
  • unzip Ubuntu Pro 14.04 LTS 6.0-9ubuntu1.6+esm1
  • unzip Ubuntu Pro 16.04 LTS 6.0-20ubuntu1.1+esm1

ubuntu advisories UBUNTU-CVE-2021-4217

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • unzip Alpine 3.24, Alpine 3.23, Alpine 3.22 +5 more 6.0-r11

alpine advisories ALPINE-CVE-2021-4217

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • unzip CBL-Mariner 2.0, Azure Linux 3.0 6.0-22

azure linux advisories AZL-10680AZL-35342

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-4217 updated cvss 3.3

unzip: Null pointer dereference in Unicode strings code

  • Red Hat Enterprise Linux 6 unzip Red Hat Enterprise Linux 7 unzip
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 unzip Red Hat Enterprise Linux 9 unzip
    affected: no fix available “Fix deferred”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-dashboard-rhel9
    under investigation

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
31 d ago

Exploit prediction

0.62% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugs.launchpad.net https://bugs.launchpad.net/ubuntu/+source/unzip/+bug/1957077 referenced PoC, tagged "exploit" by a source, unverified
  • bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=2044583 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 3.3 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

Affected products

  • n/a unzip

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.