CVE-2026-10097: ML-KEM-1024 x64 AVX2 incomplete cipher text comparison enables IND-CCA2 break and static private-key recovery

Vulnerability summary

CVE-2026-10097 is a high (CVSS 8.3) Incorrect Comparison vulnerability in wolfssl. EPSS estimates a 0.26% chance of exploitation in the next 30 days, higher than 18% of scored vulnerabilities.

Timeline

1. 25-06-2026
   PublishedVulnerability first disclosed.
2. 26-06-2026
   Last modifiedVulnerability information updated.

Description

wolfSSL's AVX2-optimized ML-KEM implementation (mlkem_cmp_avx2) compares only 1536 of the 1568 ciphertext bytes during the Fujisaki-Okamoto re-encryption check in ML-KEM-1024 decapsulation. Ciphertexts that differ from the expected re-encryption solely in bytes 1536-1567 bypass implicit rejection and are accepted as valid, breaking IND-CCA2 security. An attacker able to submit chosen ciphertexts to a decapsulation oracle that uses a static ML-KEM-1024 key, and to observe whether the genuine shared secret or the implicit-rejection secret was produced, can use this as a plaintext-checking oracle to recover the private key. A proof of concept recovered a full ML-KEM-1024 private key with approximately 98% success using roughly 350 chosen ciphertexts. The flaw is a deterministic logic error and does not rely on timing measurements.

• CWE-697Incorrect ComparisonThe product compares two entities in a security-relevant context, but the comparison is incorrect.