An issue was discovered in the yh_create_session() function of yubihsm-shell through 2.0.2. The function does not explicitly check the returned session id from the device. An invalid session id would lead to out-of-bounds read and write operations in the session array. This could be used by an attacker to cause a denial of service attack.
https://www.yubico.com/support/security-advisories/ysa-2020-06/
https://github.com/Yubico/yubihsm-shell