The process_open function in sftp-server.c in OpenSSH before 7.6 does not properly prevent write operations in readonly mode, which allows attackers to create zero-length files.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:NI:LA:N5.3/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N