CVE-2026-6550
CVE-2026-6550 is a medium-severity vulnerability with a CVSS 3.x base score of 4.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-757.
Key facts
- Severity: Medium (CVSS 3.x base score 4.7)
- CVSS v4: 5.7
- EPSS exploit prediction: 0% (1st percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-23943
- Weakness: CWE-757
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-6550?
- 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.
- How severe is CVE-2026-6550?
- CVE-2026-6550 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
- Is CVE-2026-6550 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-6550?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2026-6550 have an EU (EUVD) identifier?
- Yes. CVE-2026-6550 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23943.
- When was CVE-2026-6550 published?
- CVE-2026-6550 was published on 2026-04-20 and last updated on 2026-06-17.
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
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