CVE-2020-8911 CBC padding oracle in AWS S3 Crypto SDK for GoLang
An attacker with write access to an S3 bucket can decrypt files encrypted with the vulnerable Go SDK by exploiting a CBC padding oracle vulnerability.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2020-8911?
CVE-2020-8911 is a medium-severity vulnerability in Google LLC AWS S3 Crypto SDK for GoLang, published on 11 Aug 2020. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-327
Which versions are affected by CVE-2020-8911?
3 open source packages ship an affected version, including github.com/aws/aws-sdk-go. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/aws/aws-sdk-go Go | All versions | None |
github.com/aws/aws-sdk-go Go | All versions | 1.34.0 |
github.com/aws/aws-sdk-go Go | All versions | 1.34.0 |
Products include Amazon Aws S3 Crypto Sdk.
How do I fix CVE-2020-8911?
Upgrade github.com/aws/aws-sdk-go to 1.34.0 or later.
Is CVE-2020-8911 being exploited?
There is no known exploitation of CVE-2020-8911 in the wild and no public exploit code.
Other vulnerabilities in Google LLC AWS S3 Crypto SDK for GoLang
Sources
Also known as CLEANSTART-2026-RN39734, GHSA-f5pg-7wfw-84q9, GO-2022-0646, MINI-23mg-2m9c-pxhg, MINI-2447-rhh3-2286, MINI-24mh-x6mf-98jp and 249 more.