An issue was discovered in Mbed TLS 2.x before 2.28.7 and 3.x before 3.5.2. There was a timing side channel in RSA private operations. This side channel could be sufficient for a local attacker to recover the plaintext. It requires the attacker to send a large number of messages for decryption, as described in "Everlasting ROBOT: the Marvin Attack" by Hubert Kario.

Under certain conditions, RSA operations performed by IBM Common Cryptographic Architecture (CCA) 7.0.0 through 7.5.36 may exhibit non-constant-time behavior. This could allow a remote attacker to obtain sensitive information using a timing-based attack. IBM X-Force ID: 257676.