OpenSSH

Adversaries are abusing native Windows OpenSSH and Plink binaries to establish unauthorized reverse SSH tunnels, bypassing inbound connectivity controls for C2 and lateral movement.

Attackers may exploit SUID/SGID binaries like pkexec, su, or sudo on Linux systems to execute commands with elevated privileges, by identifying instances where a process runs with root privileges (user ID 0 or group ID 0) while the real user or group ID is non-root, allowing a low-privilege foothold to gain full system control.

CVE-2026-59998 describes an undocumented security-relevant behavior in sshd, a component of OpenSSH, specifically in versions prior to 10.4, where the GSSAPIStrictAcceptorCheck setting reportedly has no value when the server is operating within a Windows Active Directory environment.

A logic error in OpenSSH's sshd daemon before version 10.4 allowed the PermitTunnel configuration to take precedence over DisableForwarding=yes, leading to unintended SSH tunnel establishment and potential unauthorized network access through the tunnel feature.

CVE-2026-59995 describes a vulnerability in the OpenSSH sftp client, specifically versions before 10.4, that allows an attacker to control the location of downloaded files when a user executes 'sftp server:/path .' against an attacker-controlled server, potentially leading to arbitrary file placement and subsequent system compromise.

CVE-2026-59996 details a vulnerability in OpenSSH's `scp` utility, allowing a remote attacker to cause a copied file to be placed in a parent directory of the intended destination during a remote-to-remote transfer, potentially leading to unintended file system modification.

CVE-2026-59997 describes a vulnerability in the internal-sftp component of OpenSSH's sshd service, affecting versions before 10.4, where the service only processes the first nine command-line arguments, potentially leading to a bypass of security controls or unintended configuration.

Multiple vulnerabilities in OpenSSH versions prior to 10.4 allow attackers to bypass security policies, cause denial of service, and exploit other unspecified security issues, requiring users to update to OpenSSH 10.4 or later.

A vulnerability in OpenSSH could allow for authentication bypass, potentially granting an attacker root access to vulnerable servers running the protocol.