Advisory Details

July 29th, 2025

Apple Safari getHourCycles Stack-based Buffer Overflow Remote Code Execution Vulnerability

ZDI-25-673
ZDI-CAN-26616

CVE ID CVE-2025-43209
CVSS SCORE 8.8, AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
AFFECTED VENDORS Apple
AFFECTED PRODUCTS Safari
VULNERABILITY DETAILS

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Apple Safari. 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 implementation of getHourCycles API. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a fixed-length 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/124147
DISCLOSURE TIMELINE
  • 2025-06-05 - Vulnerability reported to vendor
  • 2025-07-29 - Coordinated public release of advisory
  • 2025-07-29 - Advisory Updated
CREDIT Gary Kwong
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