CVE-2026-3337 identifies a timing side-channel vulnerability in the AWS-LC cryptographic library's AES-CCM decryption implementation. Specifically, the vulnerability arises from observable timing discrepancies during the verification of the authentication tag in AES-CCM mode when using the EVP CIPHER API functions EVP_aes_128_ccm, EVP_aes_192_ccm, and EVP_aes_256_ccm. AES-CCM is a widely used authenticated encryption mode combining Counter mode encryption with CBC-MAC authentication. The timing discrepancy allows an unauthenticated attacker to measure the time taken to verify the authentication tag and infer whether the tag is valid or invalid. This information leakage can facilitate cryptanalysis attacks aimed at forging valid authentication tags or decrypting ciphertexts without the key. The vulnerability is classified under CWE-208 (Observable Timing Discrepancy), indicating that the implementation leaks sensitive information through timing variations. Exploitation does not require privileges or user interaction but demands high-precision timing measurements and repeated attempts, making it moderately difficult. AWS advises that customers using AWS services are not directly affected, as the vulnerability pertains to applications that embed AWS-LC version 1.21.0. The recommended remediation is to upgrade to AWS-LC version 1.69.0, where the timing discrepancy has been addressed. No public exploits have been reported, and the CVSS v3.1 score is 5.9 (medium severity), reflecting the moderate impact on integrity without affecting confidentiality or availability.

The primary impact of CVE-2026-3337 is on data integrity, as the timing discrepancy can allow attackers to distinguish valid from invalid authentication tags in AES-CCM encrypted messages. This could lead to forgery of authentication tags, enabling attackers to inject or modify encrypted messages undetected, potentially compromising the integrity of sensitive communications or data exchanges. While confidentiality and availability are not directly affected, successful exploitation could undermine trust in cryptographic protections, leading to broader security risks such as unauthorized command execution or data manipulation in applications relying on AWS-LC for encryption. Organizations embedding vulnerable AWS-LC versions in security-critical software, IoT devices, or network appliances may face increased risk of cryptographic attacks. The lack of authentication or user interaction requirements increases the attack surface, especially in exposed network services. However, the high complexity of exploitation and absence of known active exploits reduce immediate risk. Nonetheless, failure to patch could allow attackers with sufficient resources and access to mount targeted attacks, particularly in environments where AES-CCM is used for securing communications or data at rest.

To mitigate CVE-2026-3337, organizations should upgrade all instances of AWS-LC to version 1.69.0 or later, where the timing discrepancy has been fixed. Developers should audit their applications to identify any use of the EVP_aes_128_ccm, EVP_aes_192_ccm, or EVP_aes_256_ccm APIs and ensure these calls are updated to the patched library version. Implementing constant-time cryptographic operations is critical; therefore, reviewing custom cryptographic code or wrappers around AWS-LC for timing leaks is advised. Network-level mitigations include rate limiting and anomaly detection to identify unusual patterns of authentication tag verification attempts that could indicate timing attacks. Organizations should also consider deploying cryptographic libraries with formal verification or side-channel resistance guarantees for high-security environments. Monitoring vendor advisories for updates and applying patches promptly is essential. Finally, security teams should conduct threat modeling to assess exposure of AES-CCM encrypted channels and prioritize remediation accordingly.