CVE-2026-6330
The ML-KEM ARM64 NEON ciphertext comparison only compares half of the input, breaking the Fujisaki-Okamoto transform's implicit rejection and weakening IND-CCA2 security on that code path. The constant-time comparison effectively ignored part of the re-encrypted ciphertext, so a decapsulating party could fail to detect a manipulated ciphertext and proceed without the standard's required implicit rejection.
CSIRTS triage
- What
- The ML-KEM ARM64 NEON ciphertext comparison only checks half of the input.
- Who is affected
- Deployments using affected versions of ML-KEM.
- Urgency
- Remediation is medium urgency due to the medium severity of the issue.
- Action
- Update to a patched version for CVE-2026-6330.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.13% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 3% of all EPSS-scored CVEs.
Advisory coverage (2)
External references
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[](https://www.csirts.com/cve/CVE-2026-6330)