liboqs: Missing value barrier in FO implicit rejection path (FrodoKEM, NTRU, and others)

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-44519
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-06 22:17:51 UTC
Updated2026-11-10 21:19:30 UTC
Descriptionliboqs 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.

Risk And Classification

Primary CVSS: v3.1 5.1 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS: 0.001240000 probability, percentile 0.021610000 (date 2026-11-10)

Problem Types: CWE-385 | CWE-385 CWE-385: Covert Timing Channel

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.1MEDIUMCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
3.1CNADECLARED5.1MEDIUMCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Open-quantum-safe Liboqs affected < 0.16.0 Not specified

References

ReferenceSourceLinkTags
github.com/open-quantum-safe/liboqs/security/advisories/GHSA-5c97-hp95-vg56 [email protected] github.com
github.com/open-quantum-safe/liboqs/pull/2431 [email protected] github.com
github.com/open-quantum-safe/liboqs/commit/d95fc734f5de9bdfc80c8c65d8166... [email protected] github.com
github.com/open-quantum-safe/liboqs/releases/tag/0.16.0 [email protected] github.com
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