Vulnerability-Lookup

CVE-2026-6550 (GCVE-0-2026-6550)

Vulnerability from cvelistv5 – Published: 2026-04-20 19:20 – Updated: 2026-04-20 19:44

Title

Key commitment policy bypass via shared key cache in AWS Encryption SDK for Python

Summary

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.

Severity

4.7 (Medium)


                        
                          CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

5.7 (Medium)


                        
                          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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-20 19:44 UTC

CWE

CWE-757 - Selection of Less-Secure algorithm during negotiation ('algorithm downgrade')

Assigner

AMZN CNA under the mitre root

CNA scorecard A 94/100 over 136 records in the last 180 days details

References

4 references

URL	Tags
https://aws.amazon.com/security/security-bulletin…	vendor-advisory
https://github.com/aws/aws-encryption-sdk-python/…	patch
https://github.com/aws/aws-encryption-sdk-python/…	patch
https://github.com/aws/aws-encryption-sdk-python/…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version	CPE status
AWS	AWS Encryption SDK for Python	Affected: 2 , ≤ 2.5.1 (custom) Affected: 3 , ≤ 3.3.0 (custom) Affected: 4 , ≤ 4.0.4 (custom)	guessed

Credits

1seal.org

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-6550",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-20T19:44:04.637540Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-20T19:44:11.685Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "AWS Encryption SDK for Python",
          "vendor": "AWS",
          "versions": [
            {
              "lessThanOrEqual": "2.5.1",
              "status": "affected",
              "version": "2",
              "versionType": "custom"
            },
            {
              "lessThanOrEqual": "3.3.0",
              "status": "affected",
              "version": "3",
              "versionType": "custom"
            },
            {
              "lessThanOrEqual": "4.0.4",
              "status": "affected",
              "version": "4",
              "versionType": "custom"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "1seal.org"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eCryptographic 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.\u003c/p\u003e\u003cp\u003eTo remediate this issue, users should upgrade to version 3.3.1, 4.0.5 or above.\u003c/p\u003e"
            }
          ],
          "value": "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."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-620",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-620 Drop Encryption Level"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "LOCAL",
            "availabilityImpact": "NONE",
            "baseScore": 4.7,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        },
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
            "attackVector": "LOCAL",
            "baseScore": 5.7,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "LOW",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-757",
              "description": "CWE-757 Selection of Less-Secure algorithm during negotiation (\u0027algorithm downgrade\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-20T19:24:09.971Z",
        "orgId": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
        "shortName": "AMZN"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://aws.amazon.com/security/security-bulletins/2026-017-aws/"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1"
        },
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "Key commitment policy bypass via shared key cache in AWS Encryption SDK for Python",
      "x_generator": {
        "engine": "Vulnogram 1.0.1"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
    "assignerShortName": "AMZN",
    "cveId": "CVE-2026-6550",
    "datePublished": "2026-04-20T19:20:23.383Z",
    "dateReserved": "2026-04-17T20:06:20.299Z",
    "dateUpdated": "2026-04-20T19:44:11.685Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-6550",
      "date": "2026-10-15",
      "epss": "0.00099",
      "percentile": "0.00778"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "AWS Encryption SDK for Python",
                "vendor": "AWS",
                "versions": [
                  {
                    "lessThanOrEqual": "2.5.1",
                    "status": "affected",
                    "version": "2",
                    "versionType": "custom"
                  },
                  {
                    "lessThanOrEqual": "3.3.0",
                    "status": "affected",
                    "version": "3",
                    "versionType": "custom"
                  },
                  {
                    "lessThanOrEqual": "4.0.4",
                    "status": "affected",
                    "version": "4",
                    "versionType": "custom"
                  }
                ]
              }
            ],
            "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "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."
          }
        ],
        "id": "CVE-2026-6550",
        "lastModified": "2026-06-17T11:00:57.820",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "HIGH",
                "attackVector": "LOCAL",
                "availabilityImpact": "NONE",
                "baseScore": 4.7,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N",
                "version": "3.1"
              },
              "exploitabilityScore": 1.0,
              "impactScore": 3.6,
              "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
              "type": "Secondary"
            }
          ],
          "cvssMetricV40": [
            {
              "cvssData": {
                "Automatable": "NOT_DEFINED",
                "Recovery": "NOT_DEFINED",
                "Safety": "NOT_DEFINED",
                "attackComplexity": "HIGH",
                "attackRequirements": "PRESENT",
                "attackVector": "LOCAL",
                "availabilityRequirement": "NOT_DEFINED",
                "baseScore": 5.7,
                "baseSeverity": "MEDIUM",
                "confidentialityRequirement": "NOT_DEFINED",
                "exploitMaturity": "NOT_DEFINED",
                "integrityRequirement": "NOT_DEFINED",
                "modifiedAttackComplexity": "NOT_DEFINED",
                "modifiedAttackRequirements": "NOT_DEFINED",
                "modifiedAttackVector": "NOT_DEFINED",
                "modifiedPrivilegesRequired": "NOT_DEFINED",
                "modifiedSubAvailabilityImpact": "NOT_DEFINED",
                "modifiedSubConfidentialityImpact": "NOT_DEFINED",
                "modifiedSubIntegrityImpact": "NOT_DEFINED",
                "modifiedUserInteraction": "NOT_DEFINED",
                "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
                "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
                "modifiedVulnIntegrityImpact": "NOT_DEFINED",
                "privilegesRequired": "LOW",
                "providerUrgency": "NOT_DEFINED",
                "subAvailabilityImpact": "NONE",
                "subConfidentialityImpact": "NONE",
                "subIntegrityImpact": "NONE",
                "userInteraction": "NONE",
                "valueDensity": "NOT_DEFINED",
                "vectorString": "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",
                "version": "4.0",
                "vulnAvailabilityImpact": "NONE",
                "vulnConfidentialityImpact": "NONE",
                "vulnIntegrityImpact": "HIGH",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
              },
              "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
              "type": "Secondary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2026-6550",
                "options": [
                  {
                    "exploitation": "none"
                  },
                  {
                    "automatable": "no"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-20T19:44:04.637540Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2026-04-20T20:16:49.283",
        "references": [
          {
            "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
            "url": "https://aws.amazon.com/security/security-bulletins/2026-017-aws/"
          },
          {
            "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
            "url": "https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1"
          },
          {
            "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
            "url": "https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5"
          },
          {
            "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
            "url": "https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv"
          }
        ],
        "sourceIdentifier": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
        "vulnStatus": "Awaiting Analysis",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-757"
              }
            ],
            "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
            "type": "Secondary"
          }
        ]
      }
    },
    "redhat_vex": {
      "current_release_date": "2026-06-05T19:31:55+00:00",
      "cve": "CVE-2026-6550",
      "id": "CVE-2026-6550",
      "initial_release_date": "2026-01-01T00:00:00+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "Key commitment policy bypass via shared key cache in AWS Encryption SDK for Python",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6550.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2026-6550",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-04-20T19:44:04.637540Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-04-20T19:44:07.480Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unaffected",
              "product": "AWS Encryption SDK for Python",
              "vendor": "AWS",
              "versions": [
                {
                  "lessThanOrEqual": "2.5.1",
                  "status": "affected",
                  "version": "2",
                  "versionType": "custom"
                },
                {
                  "lessThanOrEqual": "3.3.0",
                  "status": "affected",
                  "version": "3",
                  "versionType": "custom"
                },
                {
                  "lessThanOrEqual": "4.0.4",
                  "status": "affected",
                  "version": "4",
                  "versionType": "custom"
                }
              ]
            }
          ],
          "credits": [
            {
              "lang": "en",
              "type": "finder",
              "value": "1seal.org"
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "supportingMedia": [
                {
                  "base64": false,
                  "type": "text/html",
                  "value": "\u003cp\u003eCryptographic 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.\u003c/p\u003e\u003cp\u003eTo remediate this issue, users should upgrade to version 3.3.1, 4.0.5 or above.\u003c/p\u003e"
                }
              ],
              "value": "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."
            }
          ],
          "impacts": [
            {
              "capecId": "CAPEC-620",
              "descriptions": [
                {
                  "lang": "en",
                  "value": "CAPEC-620 Drop Encryption Level"
                }
              ]
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "attackComplexity": "HIGH",
                "attackVector": "LOCAL",
                "availabilityImpact": "NONE",
                "baseScore": 4.7,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N",
                "version": "3.1"
              },
              "format": "CVSS",
              "scenarios": [
                {
                  "lang": "en",
                  "value": "GENERAL"
                }
              ]
            },
            {
              "cvssV4_0": {
                "Automatable": "NOT_DEFINED",
                "Recovery": "NOT_DEFINED",
                "Safety": "NOT_DEFINED",
                "attackComplexity": "HIGH",
                "attackRequirements": "PRESENT",
                "attackVector": "LOCAL",
                "baseScore": 5.7,
                "baseSeverity": "MEDIUM",
                "exploitMaturity": "NOT_DEFINED",
                "privilegesRequired": "LOW",
                "providerUrgency": "NOT_DEFINED",
                "subAvailabilityImpact": "NONE",
                "subConfidentialityImpact": "NONE",
                "subIntegrityImpact": "NONE",
                "userInteraction": "NONE",
                "valueDensity": "NOT_DEFINED",
                "vectorString": "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",
                "version": "4.0",
                "vulnAvailabilityImpact": "NONE",
                "vulnConfidentialityImpact": "NONE",
                "vulnIntegrityImpact": "HIGH",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
              },
              "format": "CVSS",
              "scenarios": [
                {
                  "lang": "en",
                  "value": "GENERAL"
                }
              ]
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-757",
                  "description": "CWE-757 Selection of Less-Secure algorithm during negotiation (\u0027algorithm downgrade\u0027)",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-04-20T19:24:09.971Z",
            "orgId": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
            "shortName": "AMZN"
          },
          "references": [
            {
              "tags": [
                "vendor-advisory"
              ],
              "url": "https://aws.amazon.com/security/security-bulletins/2026-017-aws/"
            },
            {
              "tags": [
                "patch"
              ],
              "url": "https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5"
            },
            {
              "tags": [
                "patch"
              ],
              "url": "https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1"
            },
            {
              "tags": [
                "third-party-advisory"
              ],
              "url": "https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv"
            }
          ],
          "source": {
            "discovery": "UNKNOWN"
          },
          "title": "Key commitment policy bypass via shared key cache in AWS Encryption SDK for Python",
          "x_generator": {
            "engine": "Vulnogram 1.0.1"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
        "assignerShortName": "AMZN",
        "cveId": "CVE-2026-6550",
        "datePublished": "2026-04-20T19:20:23.383Z",
        "dateReserved": "2026-04-17T20:06:20.299Z",
        "dateUpdated": "2026-04-20T19:44:11.685Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

FKIE_CVE-2026-6550

Vulnerability from fkie_nvd - Published: 2026-04-20 20:16 - Updated: 2026-06-17 11:00

Severity

4.7 (Medium) - CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

Summary

References

	URL	Tags
	ff89ba41-3aa1-4d27-914a-91399e9639e5	https://aws.amazon.com/security/security-bulletins/2026-017-aws/
	ff89ba41-3aa1-4d27-914a-91399e9639e5	https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1
	ff89ba41-3aa1-4d27-914a-91399e9639e5	https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5
	ff89ba41-3aa1-4d27-914a-91399e9639e5	https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "AWS Encryption SDK for Python",
          "vendor": "AWS",
          "versions": [
            {
              "lessThanOrEqual": "2.5.1",
              "status": "affected",
              "version": "2",
              "versionType": "custom"
            },
            {
              "lessThanOrEqual": "3.3.0",
              "status": "affected",
              "version": "3",
              "versionType": "custom"
            },
            {
              "lessThanOrEqual": "4.0.4",
              "status": "affected",
              "version": "4",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    }
  ],
  "id": "CVE-2026-6550",
  "lastModified": "2026-06-17T11:00:57.820",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "LOCAL",
          "availabilityImpact": "NONE",
          "baseScore": 4.7,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 1.0,
        "impactScore": 3.6,
        "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
        "type": "Secondary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "HIGH",
          "attackRequirements": "PRESENT",
          "attackVector": "LOCAL",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 5.7,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "LOW",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "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",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-6550",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-04-20T19:44:04.637540Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-04-20T20:16:49.283",
  "references": [
    {
      "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
      "url": "https://aws.amazon.com/security/security-bulletins/2026-017-aws/"
    },
    {
      "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
      "url": "https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1"
    },
    {
      "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
      "url": "https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5"
    },
    {
      "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
      "url": "https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv"
    }
  ],
  "sourceIdentifier": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-757"
        }
      ],
      "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
      "type": "Secondary"
    }
  ]
}

GHSA-V638-38FC-RHFV

Vulnerability from github – Published: 2026-04-24 15:59 – Updated: 2026-04-24 15:59

Summary

AWS Encryption SDK for Python: Key commitment policy bypass via shared key cache

Details

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-vphw-hphf). A threat actor who controls ciphertext can cause a recipient to decrypt a message different from what the sender encrypted, breaking message integrity.

Impacted versions

From 2.0 to 2.5.1
From 3.0 to 3.3.0
From 4.0 to 4.0.4

Patches

This issue has been addressed in ESDK for Python versions 3.3.1 and 4.0.5. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.

Workarounds

If a customer requires operating multiple instances of the Python ESDK each with differently configured key commitment policies, they must not share a key cache.

References If there are any questions or comments about this advisory, contact AWS Security through the vulnerability reporting page or directly via email to aws-security@amazon.com. Please do not create a public GitHub issue.

Acknowledgement

Thanks to 1seal.org for collaborating on this issue through the coordinated vulnerability disclosure process.

Severity

4.7 (Medium)


                  
                    CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

5.7 (Medium)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c 3.3.0"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "aws-encryption-sdk"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.0.0"
            },
            {
              "fixed": "3.3.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c 4.0.4"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "aws-encryption-sdk"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.0.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-6550"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-757"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-24T15:59:17Z",
    "nvd_published_at": "2026-04-20T20:16:49Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\nAWS 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.\n\n## Impact\nThis 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.\n\nThese conditions may occur during a migration from ESDK for Python v1 to newer versions, as v1 did not support key commitment.\n\nWhen the weaker-policy client encrypts first, the cache stores encryption materials that do not enforce key commitment. Subsequent callers \u2014 including those configured to require key commitment \u2014 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-vphw-hphf). A threat actor who controls ciphertext can cause a recipient to decrypt a message different from what the sender encrypted, breaking message integrity.\n\n## Impacted versions\n- From 2.0 to 2.5.1\n- From 3.0 to 3.3.0\n- From 4.0 to 4.0.4\n\n## Patches\nThis issue has been addressed in ESDK for Python versions 3.3.1 and 4.0.5. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.\n\n## Workarounds\nIf a customer requires operating multiple instances of the Python ESDK each with differently configured key commitment policies, they must not share a key cache.\n\nReferences\nIf there are any questions or comments about this advisory, contact AWS Security through the [vulnerability reporting page](https://aws.amazon.com/security/vulnerability-reporting) or directly via email to [aws-security@amazon.com](mailto:aws-security@amazon.com). Please do not create a public GitHub issue.\n\n## Acknowledgement\nThanks to [1seal.org](http://1seal.org/) for collaborating on this issue through the coordinated vulnerability disclosure process.",
  "id": "GHSA-v638-38fc-rhfv",
  "modified": "2026-04-24T15:59:17Z",
  "published": "2026-04-24T15:59:17Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv"
    },
    {
      "type": "WEB",
      "url": "https://github.com/google/security-research/security/advisories/GHSA-wqgp-vphw-hphf"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6550"
    },
    {
      "type": "WEB",
      "url": "https://aws.amazon.com/security/security-bulletins/2026-017-aws"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/aws/aws-encryption-sdk-python"
    },
    {
      "type": "WEB",
      "url": "https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "AWS Encryption SDK for Python: Key commitment policy bypass via shared key cache"
}

PYSEC-2026-2387

Vulnerability from pysec - Published: 2026-07-13 15:02 - Updated: 2026-07-13 16:03

Details

Summary

Impact

These conditions may occur during a migration from ESDK for Python v1 to newer versions, as v1 did not support key commitment.

Impacted versions

From 2.0 to 2.5.1
From 3.0 to 3.3.0
From 4.0 to 4.0.4

Patches

Workarounds

If a customer requires operating multiple instances of the Python ESDK each with differently configured key commitment policies, they must not share a key cache.

Acknowledgement

Thanks to 1seal.org for collaborating on this issue through the coordinated vulnerability disclosure process.

Severity

4.7 (Medium)


                  
                    CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

5.7 (Medium)


                  
                    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

Impacted products

Name	purl
aws-encryption-sdk	pkg:pypi/aws-encryption-sdk

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "aws-encryption-sdk",
        "purl": "pkg:pypi/aws-encryption-sdk"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.0.0"
            },
            {
              "fixed": "3.3.1"
            },
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.0.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.0.0",
        "2.1.0",
        "2.2.0",
        "2.3.0",
        "2.4.0",
        "2.5.0",
        "2.5.1",
        "3.0.0",
        "3.1.0",
        "3.1.1",
        "3.2.0",
        "3.3.0",
        "4.0.0",
        "4.0.1",
        "4.0.2",
        "4.0.3",
        "4.0.4"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-6550",
    "GHSA-v638-38fc-rhfv"
  ],
  "details": "## Summary\nAWS 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.\n\n## Impact\nThis 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.\n\nThese conditions may occur during a migration from ESDK for Python v1 to newer versions, as v1 did not support key commitment.\n\nWhen the weaker-policy client encrypts first, the cache stores encryption materials that do not enforce key commitment. Subsequent callers \u2014 including those configured to require key commitment \u2014 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-vphw-hphf). A threat actor who controls ciphertext can cause a recipient to decrypt a message different from what the sender encrypted, breaking message integrity.\n\n## Impacted versions\n- From 2.0 to 2.5.1\n- From 3.0 to 3.3.0\n- From 4.0 to 4.0.4\n\n## Patches\nThis issue has been addressed in ESDK for Python versions 3.3.1 and 4.0.5. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.\n\n## Workarounds\nIf a customer requires operating multiple instances of the Python ESDK each with differently configured key commitment policies, they must not share a key cache.\n\nReferences\nIf there are any questions or comments about this advisory, contact AWS Security through the [vulnerability reporting page](https://aws.amazon.com/security/vulnerability-reporting) or directly via email to [aws-security@amazon.com](mailto:aws-security@amazon.com). Please do not create a public GitHub issue.\n\n## Acknowledgement\nThanks to [1seal.org](http://1seal.org/) for collaborating on this issue through the coordinated vulnerability disclosure process.",
  "id": "PYSEC-2026-2387",
  "modified": "2026-07-13T16:03:34.545446Z",
  "published": "2026-07-13T15:02:53.143381Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv"
    },
    {
      "type": "WEB",
      "url": "https://github.com/google/security-research/security/advisories/GHSA-wqgp-vphw-hphf"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6550"
    },
    {
      "type": "WEB",
      "url": "https://aws.amazon.com/security/security-bulletins/2026-017-aws"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/aws/aws-encryption-sdk-python"
    },
    {
      "type": "WEB",
      "url": "https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/aws-encryption-sdk"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-v638-38fc-rhfv"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "AWS Encryption SDK for Python: Key commitment policy bypass via shared key cache"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

Publication & reservation Sightings KEV catalogs Other timestamps

Loading timeline…

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-6550 (GCVE-0-2026-6550)

FKIE_CVE-2026-6550

GHSA-V638-38FC-RHFV

Summary

Impact

Impacted versions

Patches

Workarounds

Acknowledgement

PYSEC-2026-2387

Summary

Impact

Impacted versions

Patches

Workarounds

Acknowledgement

Tags

Sightings

Nomenclature

Vulnerability timeline

Related by attack behaviour