ML-KEM (Kyber) decapsulation leaks private key information through non-constant-time division in message decoding and ciphertext compression (KyberSlash)
Summary
| CVE | CVE-2024-14041 |
|---|---|
| State | PUBLISHED |
| Assigner | bcorg |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-28 08:17:12 UTC |
| Updated | 2026-07-30 16:27:52 UTC |
| Description | In Bouncy Castle for Java from 1.73 to before 1.78, three ML-KEM (CRYSTALS-Kyber) routines divided secret-derived polynomial coefficients by the modulus q: Poly.toMsg, which decodes the decrypted message, and the ciphertext compression routines Poly.compressPoly and PolyVec.compressPolyVec. An attacker able to measure the timing of a large number of decapsulations performed with the same long-term private key can recover that key. These are the KyberSlash1 (Poly.toMsg) and KyberSlash2 (ciphertext compression) divisions. Compression performed during encapsulation operates on values that become the public ciphertext and is not affected. |
Risk And Classification
Primary CVSS: v4.0 8.2 HIGH from 91579145-5d7b-4cc5-b925-a0262ff19630
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber
EPSS: 0.002750000 probability, percentile 0.196810000 (date 2026-07-30)
Problem Types: CWE-208 | CWE-208 CWE-208 Observable Timing Discrepancy
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 91579145-5d7b-4cc5-b925-a0262ff19630 | Secondary | 8.2 | HIGH | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 8.2 | HIGH | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/U:Amber |
CVSS v4.0 Breakdown
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Legion Of The Bouncy Castle Inc. | BC-JAVA | affected 1.73 1.78 maven | all |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/bcgit/bc-java/wiki/CVE-2024-14041 | 91579145-5d7b-4cc5-b925-a0262ff19630 | github.com | |
| kyberslash.cr.yp.to | 91579145-5d7b-4cc5-b925-a0262ff19630 | kyberslash.cr.yp.to | |
| github.com/bcgit/bc-java/commit/1590247178f2280defa36421475f015175dfbe9e | 91579145-5d7b-4cc5-b925-a0262ff19630 | github.com | |
| github.com/bcgit/bc-java/commit/5adb2c5c5b462a332b01a012bea0784b40b904e5 | 91579145-5d7b-4cc5-b925-a0262ff19630 | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: The Robusta team: Deepak Pillai, Anirban Chakraborty, Chitchanok Chuengsatiansup, Matthew Roughan, Peter Schwabe and Yuval Yarom (en)
CNA: The KyberSlash authors: Daniel J. Bernstein, Karthikeyan Bhargavan, Shivam Bhasin, Anupam Chattopadhyay, Tee Kiah Chia, Matthias J. Kannwischer, Franziskus Kiefer, Thales Paiva, Prasanna Ravi and Goutam Tamvada. (en)