CVE-2026-3337 identifies a timing side-channel vulnerability in the AWS-LC cryptographic library's implementation of AES-CCM decryption via the EVP CIPHER API. Specifically, the AES-128-CCM, AES-192-CCM, and AES-256-CCM cipher implementations leak observable timing differences during the authentication tag verification process. This discrepancy allows an unauthenticated attacker to infer whether an authentication tag is valid or invalid by measuring the time taken to process decryption requests. Such timing side channels can be exploited to gradually recover information about the cryptographic keys or plaintext data, undermining the integrity guarantees of AES-CCM. The vulnerability affects AWS-LC version 1.21.0 and earlier. AWS advises that customers using AWS services are not impacted, as the vulnerability is in the library used by applications rather than AWS-managed services themselves. The recommended mitigation is to upgrade AWS-LC to version 1.69.0, where the timing discrepancy has been addressed. The vulnerability is rated medium severity with a CVSS 3.1 base score of 5.9, reflecting network attack vector, high attack complexity, no privileges required, no user interaction, unchanged scope, no confidentiality impact, high integrity impact, and no availability impact. No known exploits have been reported in the wild, but the presence of a timing side channel in cryptographic operations is a significant concern for applications relying on AWS-LC for secure communications.

The primary impact of CVE-2026-3337 is on the integrity of encrypted communications that use AES-CCM via AWS-LC. An attacker capable of measuring decryption timing can potentially confirm the validity of authentication tags, which may facilitate cryptographic attacks such as forgery or plaintext recovery over time. While confidentiality and availability are not directly compromised, the integrity breach can undermine trust in secure messaging or data protection mechanisms. Organizations using AWS-LC in their applications, especially those handling sensitive or regulated data, risk exposure to subtle cryptographic attacks that could lead to data manipulation or unauthorized message acceptance. Since exploitation requires only network access and no authentication, the attack surface includes any exposed services using vulnerable AWS-LC versions. However, the high attack complexity and absence of known exploits reduce immediate risk. The vulnerability does not affect AWS-managed services, limiting impact on customers relying solely on AWS cloud services. Nonetheless, organizations embedding AWS-LC in their software stacks must address this to maintain cryptographic robustness and compliance.

To mitigate CVE-2026-3337, organizations should promptly upgrade AWS-LC to version 1.69.0 or later, where the timing discrepancy has been resolved. Developers should audit their applications to identify any direct usage of AWS-LC, particularly the EVP_aes_128_ccm, EVP_aes_192_ccm, and EVP_aes_256_ccm APIs, and ensure they are linked against the patched library version. Implementing constant-time cryptographic operations is critical; thus, reviewing and testing cryptographic code for timing side channels is recommended. Network-level protections such as rate limiting and anomaly detection can help reduce the feasibility of timing attacks by limiting attacker query volume and precision. Additionally, organizations should monitor for unusual traffic patterns that may indicate timing analysis attempts. Security teams should update threat models to include timing side-channel risks and educate developers on secure cryptographic implementation practices. Finally, maintain awareness of AWS-LC updates and advisories to promptly address future vulnerabilities.