CVE-2020-8911
CBC padding oracle in AWS S3 Crypto SDK for GoLang
- Published
- Updated
- Reserved
- Assigned by
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GoogleCNA (assigner) | 3.1 | Medium5.6 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N |
| NVDNVD · Modified | 3.1 | Medium5.6 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N |
- EPSS (exploitation in 30 days)
- 0.35% · top 72% of all CVEs (6 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.6.
Weakness
Affected products
Google LLC · AWS S3 Crypto SDK for GoLang
- affected stable – ≤ V1
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Gogithub.com/aws/aws-sdk-goGHSA-f5pg-7wfw-84q9 (opens in a new tab)
References (2)
- https://aws.amazon.com/blogs/developer/updates-to-the-amazon-s3-encryption-client/?s=09 (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://github.com/google/security-research/security/advisories/GHSA-f5pg-7wfw-84q9 (opens in a new tab)x_refsource_CONFIRMx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-f5pg-7wfw-84q9 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2020-8911)Record last updated .