Apple macOS libFontParser TTF Font Parsing Out-Of-Bounds Read Information Disclosure Vulnerability

August 5th, 2021
ZDI-21-945 ZDI-CAN-13505

CVE ID

CVE-2021-30788

CVSS Score

4.3 AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Affected Vendors

Apple

Affected Products

macOS

Vulnerability Details

This vulnerability allows remote attackers to disclose sensitive information on affected installations of Apple macOS. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.

The specific flaw exists within the ApplyAllPointDeltas function in libFontParser. Crafted data in a TTF font can trigger a read past the end of an allocated data structure. An attacker can leverage this in conjunction with other vulnerabilities to execute arbitrary 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/HT212602

Disclosure Timeline

  • 2021-05-05 - Vulnerability reported to vendor
  • 2021-08-05 - Coordinated public release of advisory

Credit

tr3e

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