CVE-2026-81721: openssl_encrypt before 1.4.9 Denial of Service via KDF
opensslencrypt before 1.4.9 fails to validate KDF cost parameters in encrypted file metadata and keystore headers, allowing attackers to trigger unbounded memory allocation. Attackers can craft malicious encrypted files declaring arbitrarily large Argon2, scrypt, or balloon KDF parameters to exhaust system memory and crash the process without authentication.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed to this denial-of-service issue?
Deployments using openssl_encrypt versions before 1.4.9 are exposed when they process attacker-controlled encrypted files or keystore headers containing KDF metadata.
What must an attacker do to trigger the issue?
An attacker can craft an encrypted file that declares arbitrarily large Argon2, scrypt, or balloon KDF cost parameters. No authentication is required.
What is the operational impact of successful exploitation?
Processing the malicious file can cause unbounded memory allocation, exhausting system memory and crashing the affected process.