{"cve":"CVE-2026-6550","nvd":{"published":"2026-04-20T20:16:49.283","modified":"2026-10-26T22:10:00.163","status":"Awaiting Analysis","description":"Cryptographic algorithm downgrade in the caching layer of Amazon AWS Encryption SDK for Python before version 3.3.1 and before version  4.0.5 might allow an authenticated local threat actor to bypass key commitment policy enforcement via a shared key cache, resulting in ciphertext that can be decrypted to multiple different plaintexts.\n\nTo remediate this issue, users should upgrade to version 3.3.1, 4.0.5 or above.","cvss_v4":{"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","score":5.7},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N","score":4.7},"cwes":["CWE-757"],"references":["https://aws.amazon.com/security/security-bulletins/2026-017-aws/","https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1","https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5","https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv"],"products":[],"source":"nvd","synced_at":"2026-10-26T22:26:44.656832877+00:00"},"epss":{"cve":"CVE-2026-6550","score":0.00096,"percentile":0.00687,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-v638-38fc-rhfv","url":"https://osv.dev/vulnerability/GHSA-v638-38fc-rhfv","summary":"AWS Encryption SDK for Python: Key commitment policy bypass via shared key cache","modified":"2026-07-13T16:43:01.768483232Z","packages":[{"ecosystem":"PyPI","name":"aws-encryption-sdk","purl":"pkg:pypi/aws-encryption-sdk","ranges":[">=2.0.0 <3.3.1"],"fixed":["3.3.1"]},{"ecosystem":"PyPI","name":"aws-encryption-sdk","purl":"pkg:pypi/aws-encryption-sdk","ranges":[">=4.0.0 <4.0.5"],"fixed":["4.0.5"]}]},{"id":"PYSEC-2026-2387","url":"https://osv.dev/vulnerability/PYSEC-2026-2387","summary":"AWS Encryption SDK for Python: Key commitment policy bypass via shared key cache","modified":"2026-07-13T16:31:31.667962786Z","packages":[{"ecosystem":"PyPI","name":"aws-encryption-sdk","purl":"pkg:pypi/aws-encryption-sdk","ranges":[">=2.0.0 <3.3.1",">=4.0.0 <4.0.5"],"fixed":["3.3.1","4.0.5"]}]}],"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."]}