openssl_encrypt CVE-2026-81704

Exploitation requires the attacker to first obtain a copy of a file encrypted by openssl_encrypt before version 1.4.9 via the D-Bus CryptoService.EncryptFile handler; acquisition can occur through any means including exfiltration, exposed storage, physical media access, or backup compromise. Once the encrypted file is in hand, no further access to the target system is required - cracking proceeds entirely offline with no authentication, no network access, and no special configuration needed. The vulnerability affects all files encrypted by the handler regardless of settings; no non-default configuration limits or extends exposure. Exploitation is strictly limited to confidentiality of encrypted file contents; there is no integrity or availability impact. The primary limiting factor is the need to first acquire an encrypted file, but this is a one-time precondition that many real-world threat scenarios (insider access, data breach) easily satisfy.

The CVSS 4.0 score of 8.7 with AV:N/AC:L/AT:N/PR:N/UI:N/VC:H reflects the severity of the cryptographic weakness, but the AV:N metric warrants scrutiny: D-Bus is typically a local IPC mechanism, and the primary attack path is offline cracking after file acquisition rather than direct network exploitation. The vector may be modeling the scenario where encrypted files are transmitted over a network and later cracked, which is plausible but not confirmed by the description. The VC:H and absence of integrity or availability impact accurately reflect that this is a confidentiality-only threat against file contents. No EPSS score was provided in the available data, and the vulnerability is absent from the CISA KEV catalog with no public exploit identified at time of analysis. Despite these mitigating signals, the architectural severity is high: the six-to-seven orders-of-magnitude speed advantage for attackers means that password-based confidentiality protection offered by this tool is effectively illusory against any adversary with GPU resources. Organizations using openssl_encrypt to protect sensitive documents should treat remediation as urgent - the real risk is not a network intrusion but the silent invalidation of past encryption operations, which cannot be fixed retroactively without re-encrypting all affected files. The niche deployment footprint limits aggregate exposure but does not reduce per-deployment risk.

An attacker who acquires an encrypted file produced by the affected CryptoService - through a misconfigured file share, cloud storage exposure, backup leak, or insider access - loads it into a GPU-accelerated cracking tool such as Hashcat configured for raw SHA-256. Because SHA-256 can be computed at billions of guesses per second on commodity hardware, the attacker exhausts large password dictionaries and targeted candidate lists in seconds to minutes rather than years, recovering the plaintext with no further interaction with the target system. No public exploit code has been identified, but the attack requires only standard cracking tooling and knowledge of the file format's KDF construction.