Description

openssl_encrypt versions before 1.4.9 fail to validate encryption status of embedded post-quantum private keys in file metadata. Attackers can craft files with unencrypted embedded PQC keys that decrypt under any password, bypassing authentication and producing attacker-chosen plaintext with false integrity verification.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.5",
  "pubDate": "2026-08-27T17:21:00.833Z",
  "pubdate": "2026-08-27T17:21:00.833Z",
  "executiveSummary": "A critical security vulnerability exists in openssl_encrypt versions prior to 1.4.9 involving the improper validation of encryption status for embedded post-quantum cryptographic (PQC) private keys within file metadata. The vulnerability stems from a failure to verify whether these sensitive keys are correctly encrypted before processing them.\nThis flaw allows a remote attacker to craft malicious files containing unencrypted embedded PQC keys. When the target system processes these files, the lack of status validation causes the application to treat the unencrypted keys as valid. Consequently, the affected system may decrypt data under arbitrary password inputs, effectively bypassing authentication mechanisms. This facilitates the production of attacker-chosen plaintext while simultaneously generating false integrity verification signals.\nThe risk to the organization is severe, as it undermines the fundamental cryptographic assurance provided by the library. An attacker with the ability to supply a malicious file can compromise data confidentiality and integrity without prior authentication. The vulnerability impacts all systems utilizing openssl_encrypt versions below 1.4.9 that handle files with PQC metadata. Immediate remediation through version updates is required to mitigate the risk of unauthorized data access and integrity subversion.",
  "technicalDetails": "The root cause of this vulnerability lies in an insufficient metadata inspection process within the openssl_encrypt function. When processing files, the library fails to enforce a cryptographically mandatory check on the encryption state flag of embedded post-quantum cryptographic (PQC) private keys. In a secure implementation, the library should verify that the key material is encapsulated by an authenticated encryption scheme before proceeding; however, the vulnerable code branches omit this validation step.\nThe exploitation flow begins when an attacker crafts a malicious file, embedding an unencrypted PQC private key in the file's metadata section. The attacker specifically omits the expected cryptographic headers or flags that would normally indicate that the key is encrypted at rest. When openssl_encrypt parses this file, the routine fails to validate the encryption status against the expected security policy. Because the internal logic does not assert that the key must be encrypted, it proceeds to initialize the decryption context using the unencrypted key material.\nDuring the decryption phase, the library accepts any user-provided password as a valid credential, as the underlying key is effectively 'naked' and accessible. This design flaw allows the attacker to force the decryption process to complete successfully regardless of the provided password. Furthermore, because the library's internal state reflects a successful decryption operation, the system produces plaintext data that appears valid to the application layer. Crucially, the library also returns a positive integrity verification status, misleading the application into trusting the attacker-injected plaintext.\nThis vulnerability is particularly dangerous because it facilitates a complete bypass of authentication. The attacker-chosen plaintext can be used to inject malicious commands, modify sensitive data, or forge digital signatures if the PQC keys are used for identity verification. Since the library erroneously reports the integrity of the data as verified, the downstream application components have no mechanism to detect that the processed content is malicious. The attack does not require high-level privileges; the primary requirement is the ability to submit a crafted file to a system utilizing an unpatched version of the openssl_encrypt function. The failure is persistent across versions prior to 1.4.9, impacting all standard library operations that invoke the affected metadata parsing functions for post-quantum cryptographic assets."
}