CVE-2023-3603

A missing allocation check in sftp server processing read requests may cause a NULL dereference on low-memory conditions. The malicious client can request up to 4GB SFTP reads, causing allocation of up to 4GB buffers, which was not being checked for failure. This will likely crash the authenticated user's sftp server connection (if implemented as forking as recommended). For thread-based servers, this might also cause DoS for legitimate users.

Given this code is not in any released versions, no security releases have been issued.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

The SFTP server implementation is based on callbacks so you can rewrite the sftp_channel_default_data_callback() to provide additional checks.

[1] https://gitlab.com/libssh/libssh-mirror/-/blob/master/examples/sample_sftpserver.c#L330