The fontconfig project has an off-by-one error (CWE-193) in versions prior to 2.17.1, specifically in the FcFontCapabilities function in fcfreetype.c. This error results in a one-byte out-of-bounds write during sfnt capability handling, which may cause application crashes or potentially enable code execution. The vulnerability has a CVSS 3.1 base score of 5.9, reflecting medium severity with local attack vector, low complexity, no privileges required, no user interaction, and impacts on confidentiality, integrity, and availability.

Exploitation of this vulnerability can lead to a one-byte out-of-bounds write, which may cause application crashes or potentially allow an attacker to execute arbitrary code. The impact affects confidentiality, integrity, and availability to a limited extent. No known exploits have been reported in the wild.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch or official fix information is provided, users should monitor the fontconfig project for updates and apply any official patches once available. Until then, consider limiting exposure by restricting access to affected fontconfig components where feasible.