openssl_encrypt versions before 1.4.9 use under-parameterized PBKDF2-HMAC-SHA256 with only 100,000 iterations to protect PQC keyfile private keys and 10,000 iterations for dual-encryption file-password verification. Attackers who obtain keyfiles or encrypted files can brute-force wrapping passwords offline using GPU or ASIC acceleration.

openssl_encrypt versions prior to 1.4.9 employ under-parameterized PBKDF2-HMAC-SHA256 key derivation, using only 100,000 iterations for PQC keyfile private key protection and a mere 10,000 iterations for dual-encryption file-password verification. These iteration counts are considered insufficient against modern GPU and ASIC-accelerated brute-force attacks. Attackers who gain access to keyfiles or encrypted files can perform offline password brute-forcing at high speed. The vulnerability affects the confidentiality of wrapped private keys and file encryption passwords. Users are advised to upgrade to version 1.4.9 or later, which presumably addresses these weak cryptographic parameters. The issue is tracked as CVE-2026-81718 and has been published by NVD, GitHub Security Advisories, and VulnCheck.