CVE-2024-14041

ML-KEM (Kyber) decapsulation leaks private key information through non-constant-time division in message decoding and ciphertext compression (KyberSlash)

MEDIUM
5.9
CVSS Score
Published: July 28, 2026 at 08:05 AM UTC
Updated: October 2, 2026 at 12:10 AM UTC
2 products affected across 2 vendorsBc JavaBC Java

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Severity
MEDIUM5.9
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

1.73 ≤ v < 1.78
Affected range stops below 1.78, so it looks safe — our inference, not a vendor statement
1.73 ≤ v < 1.781.73
Affected range stops below 1.78, so it looks safe — our inference, not a vendor statement

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-208

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