Advisory Details

This vulnerability allows remote attackers to execute arbitrary code on affected installations of FontForge. 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 parsing of SFD files. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated array. An attacker can leverage this vulnerability to execute code in the context of the current user.

12/12/25 - ZDI submitted the reports to the vendor via third-party platform
12/13/25 - ZDI reached out to the vendor’s GitHub account
12/13/24 – the vendor rejected the vulnerability, stating that only pull requests that include the required fixes will be considered
12/15/25 – ZDI notified the vendor of the intention to publish the case as a 0-day advisory on 12/29/25

-- Mitigation: Given the nature of the vulnerability, the only salient mitigation strategy is to restrict interaction with the product

• 2025-12-12 - Vulnerability reported to vendor
• 2025-12-29 - Coordinated public release of advisory
• 2025-12-29 - Advisory Updated