---
id: "CVE-2026-44519"
page: "https://infrastack.ai/live/CVE-2026-44519"
kind: "vulnerability"
aliases: ["CVE-2026-44519"]
title: "liboqs: FrodoKEM decapsulation leaks secrets via cache timing under -Os"
severity: "medium"
cvss: 5.1
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["c", "clang", "liboqs", "package", "post-quantum"]
not_affected_if: ["default-o3-build", "liboqs-0.16.0-or-later", "no-frodokem"]
published_at: "2026-11-06T22:17:51+00:00"
first_seen_at: "2026-11-06T22:44:32+00:00"
updated_at: "2026-11-06T22:44:59+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44519", "first_seen_at": "2026-11-06T22:44:32+00:00"}]
exploit_sources: []
---

# liboqs: FrodoKEM decapsulation leaks secrets via cache timing under -Os

Link for people: https://infrastack.ai/live/CVE-2026-44519 (this .md is for agents)

liboqs, a C post-quantum cryptography library, has a missing value barrier in its FrodoKEM ct_select routine that Clang 17+ can compile into a secret-dependent memory access at -Os. A local attacker running repeated cache-timing measurements can use this as an oracle toward private-key recovery.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the liboqs version your build links against, for example `liboqs` in your package manifest or `oqs_version()`.
- Check whether you build FrodoKEM with Clang 17 or later at `-Os` rather than the default `-O3`.

## Fix

- liboqs: move to `0.16.0` or later.

## Timeline

- 2026-11-06T22:44:32+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-44519

## Documents

- [advisory] Vendor advisory: github.com https://github.com/open-quantum-safe/liboqs/security/advisories/GHSA-5c97-hp95-vg56
- [fix] Patch: github.com https://github.com/open-quantum-safe/liboqs/commit/d95fc734f5de9bdfc80c8c65d8166b30e9cff5cd
- [fix] Release notes: github.com https://github.com/open-quantum-safe/liboqs/releases/tag/0.16.0

## From the sources

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Prior to 0.16.0, the ct_select function in src/kem/frodokem/external/util.c for the FrodoKEM-640, FrodoKEM-976, and FrodoKEM-1344 AES and SHAKE reference variants lacks a value barrier in the Fujisaki-Okamoto implicit-rejection path. When compiled with Clang 17 or later at an affected optimization level such as -Os, the compiler can emit a secret-dependent conditional load, causing the real and rejection secret paths to leave distinguishable cache residency after successful and failed decapsulation. A local attacker able to perform repeated cache-timing measurements may use this oracle as part of a private-key recovery attack. Default -O3 builds vectorize both source loads and do not exhibit the reported behavior, and the advisory does not report the same generated memory-access pattern in NTRU, NTRU-Prime, BIKE, HQC, Classic McEliece, Kyber, or the already-barriered ML-KEM implementation. This issue is fixed in version 0.16.0.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_