CVE-2020-8911

What it is

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.

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of data exposure.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2020-08-11 20:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:27 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.3% in the next 30 days (EPSS).
• Severity: 5.6 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2020-08-11 20:15 UTC

Last modified

2026-06-17 03:27 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-327 · Broken cryptographic algorithm

Record status

Modified

Affected

• Amazon Aws s3 Crypto Sdk < 2.0

Attack profile CVSS 3.1 · 5.6

Attack vector

Local

Complexity

High

Privileges needed

Low

User interaction

None

Scope

Changed

Confidentiality

High

Integrity

None

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2020-8911.md and follow it. Check whether this project is affected by CVE-2020-8911. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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