CVE-2026-6550Key commitment policy bypass via shared key cache in AWS Encryption SDK for Python
- 5.7MediumCVSS base score
- 0.10%Exploitation in 30 daysEPSS · top 99% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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. To remediate this issue, users should upgrade to version 3.3.1, 4.0.5 or above.
Timeline
ID reserved
By AMZN
- 3 days later
· 3 days later
Published
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| AMZNCNA (assigner) | 4.0 | Medium5.7 | 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 |
| AMZNCNA (assigner) | 3.1 | Medium4.7 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N |
| NVDNVD · Awaiting Analysis | 4.0 | Medium5.7 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
- EPSS (exploitation in 30 days)
- 0.10% · top 99% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.7.
Affected products
AWS · AWS Encryption SDK for Python
- affected 2 – ≤ 2.5.1
- affected 3 – ≤ 3.3.0
- affected 4 – ≤ 4.0.4
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- PyPIaws-encryption-sdkGHSA-v638-38fc-rhfv (opens in a new tab)
References
References4
- https://aws.amazon.com/security/security-bulletins/2026-017-aws/ (opens in a new tab)vendor-advisory
- https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5 (opens in a new tab)patch
- https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1 (opens in a new tab)patch
- https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv (opens in a new tab)third-party-advisory
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)
- EUVD EUVD-2026-23943 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-v638-38fc-rhfv (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-6550)Record last updated .