{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-110310", "assignerOrgId": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "state": "PUBLISHED", "assignerShortName": "AMZN", "dateReserved": "2026-10-13T20:08:06.762Z", "datePublished": "2026-10-14T19:37:48.420Z", "dateUpdated": "2026-10-14T19:46:28.634Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "shortName": "AMZN", "dateUpdated": "2026-10-14T19:46:28.634Z"}, "title": "RSA PKCS#1 v1.5 padding oracle via legacy envelope key format downgrade in Amazon S3 Encryption Client for .NET", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-204", "description": "CWE-204 Observable response discrepancy", "type": "CWE"}]}, {"descriptions": [{"lang": "en", "cweId": "CWE-757", "description": "CWE-757 Selection of Less-Secure algorithm during negotiation ('algorithm downgrade')", "type": "CWE"}]}], "impacts": [{"capecId": "CAPEC-463", "descriptions": [{"lang": "en", "value": "CAPEC-463 Padding Oracle Crypto Attack"}]}], "affected": [{"vendor": "Amazon", "product": "Amazon.Extensions.S3.Encryption", "versions": [{"status": "affected", "version": "2.1.0", "lessThanOrEqual": "2.*", "versionType": "custom"}, {"status": "affected", "version": "3.0.0", "lessThanOrEqual": "3.2.1", "versionType": "custom"}, {"status": "affected", "version": "4.0.0", "lessThanOrEqual": "4.0.2", "versionType": "custom"}], "defaultStatus": "unaffected"}], "cpeApplicability": [{"operator": "OR", "nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:amazon:amazon.extensions.s3.encryption:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.1.0", "versionEndIncluding": "2.*"}, {"vulnerable": true, "criteria": "cpe:2.3:a:amazon:amazon.extensions.s3.encryption:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.0.0", "versionEndIncluding": "3.2.1"}, {"vulnerable": true, "criteria": "cpe:2.3:a:amazon:amazon.extensions.s3.encryption:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.0.0", "versionEndIncluding": "4.0.2"}]}]}], "descriptions": [{"lang": "en", "value": "A remote user who can read encrypted objects in the S3 bucket can force a padding downgrade by altering the padding scheme recorded in an object's metadata to legacy PKCS#1 v1.5. 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