Medium (5.5) in openquantumsafe liboqs. EPSS 0.2% chance of exploitation in the next 30 days.
liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Multiple secret-dependent branches have been identified in the reference implementation of the HQC key encapsulation mechanism when it is compiled with Clang for optimization levels above -O0 (-O1, -O2, etc). A proof-of-concept local attack exploits this secret-dependent information to recover the entire secret key. This vulnerability is fixed in 0.14.0.
Severity
CVSS 3.1
5.5 medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
EPSS
0.2% chance of exploitation in the next 30 days; higher than 14% of CVEs (scores of 2026-10-31)