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CVE-2020-8911

5.6 · MEDIUM

A padding oracle vulnerability exists in the AWS S3 Crypto SDK for GoLang versions prior to V2.

Published Aug 11, 2020CWE-327EPSS 0.35%

Overview

CVE-2020-8911 is a medium-severity vulnerability. It was published on August 11, 2020 and has a CVSS 3.1 base score of 5.6 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.6, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refaws.amazon.com/blogs/developer/updates-to-the-amazon-s3-encryption-client/?s=09GitHubgithub.com/google/security-research/security/advisories/GHSA-f5pg-7wfw-84q9Refaws.amazon.com/blogs/developer/updates-to-the-amazon-s3-encryption-client/?s=09GitHubgithub.com/google/security-research/security/advisories/GHSA-f5pg-7wfw-84q9

How CyberStrike helps

Frequently asked questions

What is CVE-2020-8911?

CVE-2020-8911 is a medium-severity vulnerability. It was published on August 11, 2020 and has a CVSS 3.1 base score of 5.6 (MEDIUM).

How severe is CVE-2020-8911?

This vulnerability has a CVSS 3.1 base score of 5.6, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2020-8911?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2020-8911?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2020-8911 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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