Advisory Details

February 4th, 2021

Apple macOS CoreText ApplyContextPosFormat2 TTF Parsing Stack-based Buffer Overflow Remote Code Execution Vulnerability

ZDI-21-140
ZDI-CAN-12153

CVE ID
CVSS SCORE 7.8, AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
AFFECTED VENDORS Apple
AFFECTED PRODUCTS macOS
VULNERABILITY DETAILS

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Apple macOS. Interaction with the CoreText library is required to exploit this vulnerability but attack vectors may vary depending on the implementation.

The specific flaw exists within the parsing of TTF fonts. Crafted data in a TTF file can trigger an overflow of a stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of the current process.
ADDITIONAL DETAILS Apple has issued an update to correct this vulnerability. More details can be found at:
https://support.apple.com/en-us/HT212147
DISCLOSURE TIMELINE
  • 2020-10-21 - Vulnerability reported to vendor
  • 2021-02-04 - Coordinated public release of advisory
CREDIT Mickey Jin of Trend Micro Mobile Security Research Team
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