Since Linux 6.9, the cryptsetup luksSuspend command no longer wipes disk-encryption keys from memory during suspend, leaving them accessible in RAM. This regression undermines the security of LUKS-encrypted devices because an attacker with physical access to a suspended system could extract the master key from memory and decrypt the disk without needing the passphrase. The issue affects Linux kernels from 6.9 onward, but not all distributions are impacted because luksSuspend is not part of the official cryptsetup specification; it originated as a Debian extension.
Background
LUKS (Linux Unified Key Setup) is a disk encryption specification that uses a master key to encrypt data on a partition. During normal operation, this master key is held in kernel memory to allow decryption on the fly. When a system is suspended to RAM, the key remains in memory, but luksSuspend was designed to wipe the key to protect against cold boot or physical attacks. The regression means the key is no longer wiped, leaving it vulnerable.
References
Discussion
Community comments highlight mixed reactions: some argue that luksSuspend is not officially supported and only affects Debian, while others emphasize that security regressions like this are easy to miss because everything still works. A few users downplay the risk, noting that after suspend, the encryption key is expected to be in memory anyway if no passphrase re-entry is required, and that disk encryption mainly protects against data theft when the drive is removed.