Vulnerabilities
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Cryptography
CVE Vulnerabilities

CVE-2021-23177

Improper Link Resolution Before File Access ('Link Following')

Published: Aug 23, 2022 | Modified: Jun 17, 2026
CVSS 3.x
7.8
HIGH
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS 2.x
RedHat/V2
RedHat/V3
7.3 MODERATE
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L
Ubuntu
LOW
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2021-23177
CWEhttps://cwe.mitre.org/data/definitions/59.html

An improper link resolution flaw while extracting an archive can lead to changing the access control list (ACL) of the target of the link. An attacker may provide a malicious archive to a victim user, who would trigger this flaw when trying to extract the archive. A local attacker may use this flaw to change the ACL of a file on the system and gain more privileges.

Weakness

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Affected Software

NameVendorStart VersionEnd Version
LibarchiveLibarchive*3.5.2 (excluding)
Red Hat Enterprise Linux 8RedHatlibarchive-0:3.3.3-3.el8_5*
LibarchiveUbuntubionic*
LibarchiveUbuntuesm-infra-legacy/trusty*
LibarchiveUbuntuesm-infra-legacy/xenial*
LibarchiveUbuntuesm-infra/bionic*
LibarchiveUbuntuesm-infra/focal*
LibarchiveUbuntuesm-infra/xenial*
LibarchiveUbuntufocal*
LibarchiveUbuntuhirsute*
LibarchiveUbuntuimpish*
LibarchiveUbuntutrusty*
LibarchiveUbuntutrusty/esm*
LibarchiveUbuntuupstream*
LibarchiveUbuntuxenial*

Potential Mitigations

  • Follow the principle of least privilege when assigning access rights to entities in a software system.
  • Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

References

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