CVE-2025-27498 in AEADs
Summary
by MITRE • 03/03/2025
aes-gcm is a pure Rust implementation of the AES-GCM. In decrypt_in_place_detached, the decrypted ciphertext (which is the correct ciphertext) is exposed even if the tag is incorrect. This is because in decrypt_inplace in asconcore.rs, tag verification causes an error to be returned with the plaintext contents still in buffer. The vulnerability is fixed in 0.4.3.
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Analysis
by VulDB Data Team • 03/03/2025
The vulnerability described in CVE-2025-27498 affects the aes-gcm crate, a pure rust implementation of the Advanced Encryption Standard with Galois/Counter Mode cryptographic algorithm. This implementation is commonly used in rust applications requiring authenticated encryption, where both confidentiality and integrity of data must be guaranteed. The flaw manifests in the decrypt_in_place_detached function which is designed to decrypt data while simultaneously verifying the authentication tag. The issue represents a critical security concern as it violates fundamental principles of authenticated encryption where incorrect authentication should prevent access to decrypted data regardless of whether the decryption process itself succeeds.
The technical root cause of this vulnerability lies in the improper handling of error conditions within the decrypt_inplace function located in the asconcore.rs file. When the authentication tag verification fails, the system correctly returns an error to indicate the authentication failure, but it fails to clear or sanitize the buffer containing the decrypted plaintext. This means that even though the decryption operation appears to succeed, the plaintext data remains accessible in memory in a potentially compromised state. The vulnerability specifically affects the decrypt_in_place_detached function which processes ciphertext and associated data without modifying the input buffer directly. This behavior creates a side-channel information leak where an attacker could potentially extract information about the plaintext through careful analysis of memory contents.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more sophisticated attacks. An attacker who can trigger tag verification failures in a system using this library could potentially recover partial or complete plaintext data from memory, undermining the security guarantees provided by authenticated encryption. This vulnerability is particularly concerning in environments where the same memory buffer might be reused for multiple decryption operations, as it could lead to cross-contamination of plaintext data between different encryption contexts. The issue represents a violation of the principle of least privilege in cryptographic operations where the system should ensure that no plaintext information is accessible when authentication fails, which is a fundamental requirement for secure authenticated encryption implementations.
This vulnerability aligns with CWE-254, which addresses 'Security Features' and specifically relates to the inadequate handling of authentication failures in cryptographic operations. The flaw also maps to ATT&CK technique T1552.003, which covers 'Unsecured Credentials' and demonstrates how improper error handling in cryptographic libraries can lead to credential exposure or data leakage. Additionally, this vulnerability corresponds to CWE-129, 'Improper Validation of Array Index', as the error handling mechanism fails to properly validate the state of the decryption buffer when authentication fails, leading to potential buffer over-read or information leakage. The fix implemented in version 0.4.3 addresses this by ensuring that when tag verification fails, the plaintext buffer is properly cleared or sanitized before returning the error, thereby preventing information leakage from the compromised decryption operation.
The mitigation strategy for this vulnerability requires immediate upgrading to version 0.4.3 or later of the aes-gcm crate. Organizations using this library should conduct thorough code reviews to identify any custom implementations or wrappers that might be affected by similar issues. Security teams should implement monitoring for any potential exploitation attempts that might involve triggering authentication failures to extract plaintext data. Additionally, developers should ensure that all cryptographic libraries are kept up-to-date and that proper error handling patterns are followed throughout the codebase to prevent similar issues from occurring in other cryptographic implementations. The vulnerability serves as a reminder of the critical importance of proper error handling in cryptographic operations and the need for thorough testing of authentication failure scenarios in security-sensitive applications.