CVE-2026-81721

openssl_encrypt before 1.4.9 (a standalone file-encryption tool by vendor jahlives, distinct from the OpenSSL library) fails to validate the key-derivation-function cost parameters recorded in encrypted file metadata and keystore headers, trusting whatever Argon2, scrypt, or balloon settings a file declares. An attacker who can get a crafted encrypted file processed, for example by uploading it to a service, sending it to a user, or placing it in an automated decryption pipeline, can declare arbitrarily large KDF cost parameters and cause the tool to attempt unbounded memory allocation. The result is memory exhaustion that crashes the decryption process, a denial of service with no code execution, no confidentiality or integrity impact, and no authentication required. Anyone running affected versions is exposed, with the greatest risk for servers, scripts, or applications that automatically decrypt files received from untrusted parties. No public proof-of-concept is known, the issue is not in CISA KEV, and EPSS assigns a 0.4% probability of exploitation in the next 30 days, so no active exploitation is currently known.

What to do: Upgrade openssl_encrypt to version 1.4.9 or later. Until upgraded, avoid decrypting files from untrusted sources with affected versions, or mitigate by validating/capping KDF cost parameters in file headers and enforcing process memory limits (e.g., ulimit or cgroup limits) on any service that decrypts externally supplied files. Audit scripts and services for invocations of openssl_encrypt on user-supplied files to identify where the tool is actually used.