CVE-2020-8911 MEDIUM

CVE-2020-8911: CBC padding oracle in AWS S3 Crypto SDK for GoLang

Vendor Google Llc
Product AWS S3 Crypto SDK for GoLang
Weakness CWE-327 · Broken crypto
Published August 11, 2020
Last update August 4, 2024

CVSS base score

5.6/10
Attack vector Local
Attack complexity High
Privileges required Low
User interaction None
Confidentiality High
Integrity None

CVSS vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

August 11, 2020 CVE published
August 4, 2024 Record updated