AI analysis
Apache MINA SSHD’s SFTP client (DefaultSftpClient in sshd-sftp) can be driven to memory exhaustion by a malicious server. When a reply arrives, the client does not check that it matches a request it previously sent, so unsolicited replies are stored and never consumed. A hostile SFTP server can keep sending those replies until the client process runs out of memory, causing a denial of service (availability only; no confidentiality or integrity impact). Any application using Apache MINA SSHD 0.9.0 through 2.19.0 or 3.0.0-M1 through 3.0.0-M5 as an SFTP client against an untrusted server is affected. There is no known public proof of concept and the issue is not listed in CISA KEV.
What to do: Upgrade Apache MINA SSHD to 2.20.0 or 3.0.0-M6, which reject unsolicited SFTP replies. Until then, do not point DefaultSftpClient (sshd-sftp) at untrusted servers, and scan application dependency trees for the affected ranges.
Affected
| Apache MINA SSHD (sshd-sftp / DefaultSftpClient) | 0.9.0 through 2.19.0 and 3.0.0-M1 through 3.0.0-M5 |
Estimated exposure
—No basis for an estimate.
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description
Possible memory exhaustion in SFTP clients (DefaultSftpClient) in component sshd-sftp in Apache MINA SSHD versions 0.9.0 to 2.19.0 and 3.0.0-M1 to 3.0.0-M5. Apache MINA SSHD is a Java library for client-side and server-side SSH. The sshd-sftp component provides support for SFTP. The SFTP client implementation, when receiving a reply, did not check that this reply corresponded to a request sent earlier. Unsolicited replies would be stored but never consumed. A malicious server could keep sending unsolicited replies until available memory in the client was exhausted. Users are recommended to upgrade to version 2.20.0 or 3.0.0-M6, which fix this issue.