Vulnerability Description
A padding oracle vulnerability exists in the AWS S3 Crypto SDK for GoLang versions prior to V2. The SDK allows users to encrypt files with AES-CBC without computing a Message Authentication Code (MAC), which then allows an attacker who has write access to the target's S3 bucket and can observe whether or not an endpoint with access to the key can decrypt a file, they can reconstruct the plaintext with (on average) 128*length (plaintext) queries to the endpoint, by exploiting CBC's ability to manipulate the bytes of the next block and PKCS5 padding errors. It is recommended to update your SDK to V2 or later, and re-encrypt your files.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Amazon | Aws S3 Crypto Sdk | < 2.0 |
Related Weaknesses (CWE)
References
- https://aws.amazon.com/blogs/developer/updates-to-the-amazon-s3-encryption-clienVendor Advisory
- https://github.com/google/security-research/security/advisories/GHSA-f5pg-7wfw-8ExploitThird Party Advisory
- https://aws.amazon.com/blogs/developer/updates-to-the-amazon-s3-encryption-clienVendor Advisory
- https://github.com/google/security-research/security/advisories/GHSA-f5pg-7wfw-8ExploitThird Party Advisory
FAQ
What is CVE-2020-8911?
CVE-2020-8911 is a vulnerability with a CVSS score of 5.6 (MEDIUM). A padding oracle vulnerability exists in the AWS S3 Crypto SDK for GoLang versions prior to V2. The SDK allows users to encrypt files with AES-CBC without computing a Message Authentication Code (MAC)...
How severe is CVE-2020-8911?
CVE-2020-8911 has been rated MEDIUM with a CVSS base score of 5.6/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2020-8911?
Check the references section above for vendor advisories and patch information. Affected products include: Amazon Aws S3 Crypto Sdk.