Vulnerability in Amazon aws-encryption-sdk (CVE-2026-6550)
Summary
Vulnerability in Amazon aws-encryption-sdk (CVE-2026-6550). Data can be tampered with by attackers. Mitigation: upgrade to 4.0.5 or later.
Original description
The description as published by the source.
Summary
AWS Encryption SDK (ESDK) for Python is a client-side encryption library. An issue exists where, under certain circumstances, a specific cryptographic algorithm downgrade in the caching layer 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.
Impact
This issue requires all of the following conditions to be true: (1) Two ESDK for Python clients with different commitment policies share a single CachingCryptoMaterialsManager instance within the same process. (2) The client with the weaker commitment policy encrypts first, warming the cache. (3) Both clients use matching encryption contexts. (4) Both clients use the pre-configured default algorithm suite.
These conditions may occur during a migration from ESDK for Python v1 to newer versions, as v1 did not support key commitment.
When the weaker-policy client encrypts first, the cache stores encryption materials that do not enforce key commitment. Subsequent callers — including those configured to require key commitment — are served these cached materials instead of generating new ones that satisfy their policy. This results in encryption without key commitment, meaning the same ciphertext can be validly decrypted to different plaintexts under different keys (the "Invisible Salamanders" issue; see https://github.com/google/security-research/security/advisories/GHSA-wqgp-…
Source: AWS Security Bulletins NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-6550 has been found in Amazon aws-encryption-sdk.
Data can be tampered with by attackers.
What to do: upgrade Amazon aws-encryption-sdk to 4.0.5 or later.
If unsure, ask your IT team or search "Amazon aws-encryption-sdk CVE-2026-6550" on the vendor's site.
CVE-2026-6550 (Amazon aws-encryption-sdk) — CWE-757
Attack vector: local / no user interaction
Patched: 4.0.5 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-757) exists in Amazon aws-encryption-sdk.
Check the vendor advisory for the affected versions of Amazon aws-encryption-sdk.
Severity: ?. Data can be tampered with by attackers.
Update to 4.0.5.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'aws-encryption-sdk' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'aws-encryption-sdk' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
aws-encryption-sdkを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Amazon aws-encryption-sdk to 4.0.5ステージング環境で 4.0.5 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- AWS aws.amazon.com
- package github.com
- web github.com
- web github.com
- web aws.amazon.com
- web github.com
- web github.com