It was discovered that libssh2 incorrectly handled certain SFTP server responses. A remote attacker controlling an SSH server could use this issue to cause libssh2 to crash or possibly execute arbitrary code. (CVE-2026-66032) It was discovered that libssh2 incorrectly handled AES-GCM cipher negotiation. A remote attacker controlling an SSH server could possibly use this issue to cause libssh2 to crash, resulting in a denial of service. (CVE-2026-66033) It was discovered that libssh2 incorrectly handled Encrypt-then-MAC cipher negotiation. A remote attacker controlling an SSH server could use this issue to cause libssh2 to crash or possibly execute arbitrary code. (CVE-2026-66035)