CVE Vulnerabilities

CVE-2021-30968

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

Published: Aug 24, 2021 | Modified: Nov 07, 2023
CVSS 3.x
5.5
MEDIUM
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CVSS 2.x
4.3 MEDIUM
AV:N/AC:M/Au:N/C:P/I:N/A:N
RedHat/V2
RedHat/V3
Ubuntu

A validation issue related to hard link behavior was addressed with improved sandbox restrictions. This issue is fixed in macOS Big Sur 11.6.2, tvOS 15.2, macOS Monterey 12.1, Security Update 2021-008 Catalina, iOS 15.2 and iPadOS 15.2, watchOS 8.3. A malicious application may be able to bypass certain Privacy preferences.

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

Name Vendor Start Version End Version
Iphone_os Apple * 15.2 (excluding)
Mac_os_x Apple 10.15 (including) 10.15.7 (excluding)
Mac_os_x Apple 10.15.7 (including) 10.15.7 (including)
Mac_os_x Apple 10.15.7-security_update_2020-001 (including) 10.15.7-security_update_2020-001 (including)
Mac_os_x Apple 10.15.7-security_update_2021-001 (including) 10.15.7-security_update_2021-001 (including)
Mac_os_x Apple 10.15.7-security_update_2021-002 (including) 10.15.7-security_update_2021-002 (including)
Mac_os_x Apple 10.15.7-security_update_2021-003 (including) 10.15.7-security_update_2021-003 (including)
Mac_os_x Apple 10.15.7-security_update_2021-004 (including) 10.15.7-security_update_2021-004 (including)
Mac_os_x Apple 10.15.7-security_update_2021-005 (including) 10.15.7-security_update_2021-005 (including)
Mac_os_x Apple 10.15.7-security_update_2021-006 (including) 10.15.7-security_update_2021-006 (including)
Mac_os_x Apple 10.15.7-security_update_2021-007 (including) 10.15.7-security_update_2021-007 (including)
Macos Apple 11.0 (including) 11.6.2 (excluding)
Macos Apple 12.0 (including) 12.1 (excluding)
Tvos Apple * 15.2 (excluding)
Watchos Apple * 8.3 (excluding)

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