Vulnerability RUSTSEC-2026-0043

Observable timing discrepancy in AES-CCM decryption in AWS-LC allows an unauthenticated user to potentially determine authentication tag validity via timing analysis.

The impacted implementations are through the EVP CIPHER API: EVP_aes_128_ccm, EVP_aes_192_ccm, and EVP_aes_256_ccm.

Customers of AWS services do not need to take action. aws-lc-fips-sys contains code from AWS-LC. Applications using aws-lc-fips-sys should upgrade to the most recent release of aws-lc-fips-sys.

Workarounds

In the special cases of using AES-CCM with (M=4, L=2), (M=8, L=2), or (M=16, L=2), applications can workaround this issue by using AES-CCM through the EVP AEAD API using implementations EVP_aead_aes_128_ccm_bluetooth, EVP_aead_aes_128_ccm_bluetooth_8, and EVP_aead_aes_128_ccm_matter respectively.

Otherwise, there is no workaround and applications using aws-lc-fips-sys should upgrade to the most recent release of aws-lc-fips-sys.