GHSA-55xh-53m6-936r: 
Java vulnerability analysis and mitigation

AWS Encryption SDK for Java versions 2.0.0 to 2.2.0 and less than 1.9.0 contains a vulnerability (CVE-2024-23680) where the software incorrectly validates some invalid ECDSA signatures. The vulnerability was discovered and disclosed on January 19, 2024, affecting the AWS Encryption SDK Java implementation (GitHub Advisory).

The vulnerability is classified as CWE-347 (Improper Verification of Cryptographic Signature) with a CVSS v3.1 base score of 5.3 (Medium). The issue specifically relates to the validation of ECDSA signatures in the encryption SDK, where certain invalid signatures could incorrectly pass validation. The vulnerability affects the streaming mode functionality where callers may stream the plaintext of signed messages before the ECDSA signature is validated (NVD).

While the vulnerability affects signature validation, there is no direct impact on the integrity of the ciphertext or decrypted plaintext due to the additional protection provided by AES-GCM encryption. However, organizations relying on ECDSA signatures for non-repudiation may be affected. An actor with trusted KMS permissions to decrypt a message may potentially be able to encrypt messages without proper signature validation (GitHub Advisory).

The vulnerability has been patched in versions 1.9.0 and 2.2.0 of the AWS Encryption SDK for Java. Users are recommended to upgrade to these versions. For those using streaming features, ensure client code reads to the end of the stream before using released plaintext. Additionally, a new API has been introduced for streaming unsigned messages, and a configuration parameter has been added to limit the number of Encrypted Data Keys (EDKs) that the ESDK will process per message (GitHub Advisory).