CVE-2020-8912

A vulnerability in the in-band key negotiation exists in the AWS S3 Crypto SDK for GoLang versions prior to V2. An attacker with write access to the targeted bucket can change the encryption algorithm of an object in the bucket, which can then allow them to change AES-GCM to AES-CTR. Using this in combination with a decryption oracle can reveal the authentication key used by AES-GCM as decrypting the GMAC tag leaves the authentication key recoverable as an algebraic equation. It is recommended to update your SDK to V2 or later, and re-encrypt your files.

• CWE-327
• CWE-327

• https://aws.amazon.com/blogs/developer/updates-to-the-amazon-s3-encryption-client/?s=09Vendor Advisory
• https://github.com/google/security-research/security/advisories/GHSA-7f33-f4f5-xwgwExploit, Third Party Advisory
• https://aws.amazon.com/blogs/developer/updates-to-the-amazon-s3-encryption-client/?s=09Vendor Advisory
• https://github.com/google/security-research/security/advisories/GHSA-7f33-f4f5-xwgwExploit, Third Party Advisory

Published

Aug 11, 2020

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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