{"id":"CVE-2026-44519","aliases":["EUVD-2026-118513","GHSA-5c97-hp95-vg56"],"status":"published","title":"liboqs: Missing value barrier in FO implicit rejection path (FrodoKEM, NTRU, and others)","description":"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.","severity":{"version":"3.1","score":5.1,"vector":"CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00124,"percentile":0.02157,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-385"],"published":"2026-11-06T21:22:27Z","modified":"2026-11-07T10:47:28Z","products":[{"vendor":"open-quantum-safe","product":"liboqs"}],"references":[{"url":"https://github.com/open-quantum-safe/liboqs/security/advisories/GHSA-5c97-hp95-vg56","tags":["x_refsource_CONFIRM","advisory"]},{"url":"https://github.com/open-quantum-safe/liboqs/pull/2431","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/open-quantum-safe/liboqs/commit/d95fc734f5de9bdfc80c8c65d8166b30e9cff5cd","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/open-quantum-safe/liboqs/releases/tag/0.16.0","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44519.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44519","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-44519","title":"liboqs: Missing value barrier in FO implicit rejection path (FrodoKEM, NTRU, and others)","description":"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.","status":"published","published":"2026-11-06T21:22:27.624Z","modified":"2026-11-06T21:22:27.624Z","cvss":[{"version":"3.1","score":5.1,"vector":"CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-385"],"updated_at":"2026-11-06T22:31:26.969657Z"}],"euvd":[{"id":"EUVD-2026-118513","description":"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.","status":"published","published":"2026-11-06T21:22:27Z","modified":"2026-11-06T21:22:27Z","cvss":[{"version":"3.1","score":5.1,"vector":"CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"updated_at":"2026-11-06T22:07:15.91214Z"}],"nvd":[{"id":"CVE-2026-44519","description":"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.","status":"published","published":"2026-11-06T22:17:51.403Z","modified":"2026-11-06T22:17:51.403Z","cvss":[{"version":"3.1","score":5.1,"vector":"CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-385"],"updated_at":"2026-11-07T00:02:36.552517Z"}],"osv":[{"id":"CVE-2026-44519","title":"liboqs: Missing value barrier in FO implicit rejection path (FrodoKEM, NTRU, and others)","description":"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.","status":"published","published":"2026-11-06T21:22:27.624Z","modified":"2026-11-09T19:17:02.869245374Z","cvss":[{"version":"3.1","score":5.1,"vector":"CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-385"],"updated_at":"2026-11-08T03:29:44.777002Z"}]}}