CVE-2024-36405: Control-flow timing leak in Kyber reference implementation when compiled with Clang 15-18 for -Os, -O1 and other options

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-06-10 · updated 2026-06-17
Weakness: CWE-208

Description

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. A control-flow timing lean has been identified in the reference implementation of the Kyber key encapsulation mechanism when it is compiled with Clang 15-18 for `-Os`, `-O1`, and other compilation options. A proof-of-concept local attack on the reference implementation leaks the entire ML-KEM 512 secret key in ~10 minutes using end-to-end decapsulation timing measurements. The issue has been fixed in version 0.10.1. As a possible workaround, some compiler options may produce vectorized code that does not leak secret information, however relying on these compiler options as a workaround may not be reliable.

Affected products

open-quantum-safe liboqs: before 0.10.1 — fixed in 0.10.1

How to fix

Upgrade to a fixed version: open-quantum-safe liboqs 0.10.1. Check the vendor advisory for mitigations.

References

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