{"cve":"CVE-2020-8911","nvd":{"published":"2020-08-11T20:15:13.230","modified":"2026-06-17T03:27:10.323","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N","score":5.6},"cwes":["CWE-327"],"references":["https://aws.amazon.com/blogs/developer/updates-to-the-amazon-s3-encryption-client/?s=09","https://github.com/google/security-research/security/advisories/GHSA-f5pg-7wfw-84q9","https://aws.amazon.com/blogs/developer/updates-to-the-amazon-s3-encryption-client/?s=09","https://github.com/google/security-research/security/advisories/GHSA-f5pg-7wfw-84q9"],"products":["amazon:aws_s3_crypto_sdk"],"source":"nvd","synced_at":"2026-10-19T21:09:20.498348299+00:00"},"epss":{"cve":"CVE-2020-8911","score":0.00346,"percentile":0.28238,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-f5pg-7wfw-84q9","url":"https://osv.dev/vulnerability/GHSA-f5pg-7wfw-84q9","summary":"CBC padding oracle issue in AWS S3 Crypto SDK for golang","modified":"2026-09-10T03:49:12.054080312Z","packages":[{"ecosystem":"Go","name":"github.com/aws/aws-sdk-go","purl":"pkg:golang/github.com/aws/aws-sdk-go","ranges":["<1.34.0"],"fixed":["1.34.0"]}]},{"id":"GO-2022-0646","url":"https://osv.dev/vulnerability/GO-2022-0646","summary":"CBC padding oracle issue in AWS S3 Crypto SDK for golang in github.com/aws/aws-sdk-go","modified":"2026-02-04T02:16:32.066930Z","packages":[{"ecosystem":"Go","name":"github.com/aws/aws-sdk-go","purl":"pkg:golang/github.com/aws/aws-sdk-go","ranges":["all versions"],"fixed":[]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}