CVE Vulnerabilities

CVE-2020-9900

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

Published: Oct 22, 2020 | Modified: Jan 09, 2023
CVSS 3.x
7.8
HIGH
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 2.x
4.6 MEDIUM
AV:L/AC:L/Au:N/C:P/I:P/A:P
RedHat/V2
RedHat/V3
Ubuntu

An issue existed within the path validation logic for symlinks. This issue was addressed with improved path sanitization. This issue is fixed in iOS 13.6 and iPadOS 13.6, macOS Catalina 10.15.6, tvOS 13.4.8, watchOS 6.2.8. A local attacker may be able to elevate their 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

Name Vendor Start Version End Version
Ipados Apple * 13.6 (excluding)
Iphone_os Apple * 13.6 (excluding)
Mac_os_x Apple * 10.15.6 (excluding)
Tvos Apple * 13.4.8 (excluding)
Watchos Apple * 6.2.8 (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