CVE-2024-56738: 
Linux Debian vulnerability analysis and mitigation

GNU GRUB (aka GRUB2) through version 2.12 contains a security vulnerability related to its cryptographic comparison function. The vulnerability stems from the implementation of grubcryptomemcmp, which does not utilize a constant-time algorithm, making it susceptible to side-channel attacks (GNU Bug, NVD).

The vulnerability exists in the grubcryptomemcmp function implementation, which uses a non-constant-time algorithm for comparing bytes. The function contains an if condition (if (pa != pb) counter++) that introduces timing variations during comparison operations, making it vulnerable to timing-based side-channel attacks. The CVSS 3.1 base score is 5.3 (MEDIUM) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N (NVD).

The vulnerability could allow attackers to perform side-channel attacks to potentially extract sensitive information through timing analysis. While the impact might be limited due to GRUB already offering commands to read arbitrary files and memory, it could still pose security risks in specific use cases (GNU Bug).

The GRUB development team plans to address this issue by switching from the current implementation to gcrypt code after updating libgcrypt (GNU Bug). Until then, no specific workarounds have been publicly announced.