Buffer overflow in Xlight FTP Server

CVE-2026-67191

Xlight FTP Server before 3.9.5 contains a pre-authentication heap buffer overflow vulnerability that allows remote unauthenticated attackers to write past the end of a heap buffer by sending a malformed SSH client identification string. A logic error in the recv loop's termination condition uses an incorrect OR operator where an AND operator is required, enabling exploitation on any SSH or SFTP connection before authentication occurs.

Vulnerability class: Buffer Overflow

EPSS: 0.006 (47.6th percentile) — read the EPSS interpretation.