CVE-2026-81718

Received Received - Intake

OpenSSL PBKDF2 Weak Key Encryption in OpenSSL

Publication date: 2026-08-27

Last updated on: 2026-08-31

Assigner: VulnCheck

Description

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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-27

Last Modified

2026-08-31

Generated

2026-09-17

AI Q&A

2026-08-27

EPSS Evaluated

2026-09-15

NVD

CVE-2026-81718

EUVD

EUVD-2026-67068

Affected Vendors & Products

Vendor	Product	Version / Range
openssl	openssl_encrypt	to 1.4.9 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-326	The product stores or transmits sensitive data using an encryption scheme that is theoretically sound, but is not strong enough for the level of protection required.

Attack-Flow Graph

Executive Summary

This vulnerability affects openssl_encrypt versions before 1.4.9. It uses under-parameterized PBKDF2-HMAC-SHA256 with only 100,000 iterations for protecting PQC keyfile private keys and 10,000 iterations for dual-encryption file-password verification. This low iteration count makes encryption vulnerable to brute-force attacks, especially with GPU or ASIC acceleration.

Detection Guidance

Check the version of openssl_encrypt installed on your system. If it is less than 1.4.9, the system is vulnerable. Use the command: openssl_encrypt --version. Additionally, inspect keyfiles and encrypted files for weak PBKDF2 parameters by examining metadata or configuration files.

Impact Analysis

If attackers obtain keyfiles or encrypted files, they can brute-force the passwords offline. This risks unauthorized access to sensitive data protected by these weak encryption parameters.

Compliance Impact

This vulnerability weakens encryption strength by using insufficient PBKDF2 iterations, making brute-force attacks feasible. This could violate GDPR's requirement for strong encryption of personal data and HIPAA's security rule for protecting health information, as both mandate adequate safeguards against unauthorized access.

Mitigation Strategies

Upgrade openssl_encrypt to version 1.4.9 or later. For existing keyfiles, consider re-encrypting them with stronger parameters or migrating to Argon2id as recommended. Remove any legacy dual-encryption file-password verifiers and rely on AEAD tags for second-factor authentication.

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