FKIE_CVE-2026-33228

Vulnerability from fkie_nvd - Published: 2026-03-20 23:16 - Updated: 2026-06-27 05:16
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
flatted is a circular JSON parser. Prior to version 3.4.2, the parse() function in flatted can use attacker-controlled string values from the parsed JSON as direct array index keys, without validating that they are numeric. Since the internal input buffer is a JavaScript Array, accessing it with the key "__proto__" returns Array.prototype via the inherited getter. This object is then treated as a legitimate parsed value and assigned as a property of the output object, effectively leaking a live reference to Array.prototype to the consumer. Any code that subsequently writes to that property will pollute the global prototype. This issue has been patched in version 3.4.2.
References
security-advisories@github.comhttps://github.com/WebReflection/flatted/commit/885ddcc33cf9657caf38c57c7be45ae1c5272802Patch
security-advisories@github.comhttps://github.com/WebReflection/flatted/releases/tag/v3.4.2Product
security-advisories@github.comhttps://github.com/WebReflection/flatted/security/advisories/GHSA-rf6f-7fwh-wjghExploit, Vendor Advisory
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:13826
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:9742
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/security/cve/CVE-2026-33228
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://bugzilla.redhat.com/show_bug.cgi?id=2449872
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33228.json
Impacted products
Vendor Product Version
webreflection flatted *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "flatted",
          "vendor": "WebReflection",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.4.2"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    },
    {
      "affectedData": [
        {
          "cpes": [
            "cpe:/a:redhat:rhdh:1.8::el9"
          ],
          "defaultStatus": "affected",
          "product": "Red Hat Developer Hub 1.8",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:rhdh:1.9::el9"
          ],
          "defaultStatus": "affected",
          "product": "Red Hat Developer Hub 1.9",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:red_hat_3scale_amp:2"
          ],
          "defaultStatus": "affected",
          "product": "Red Hat 3scale API Management Platform 2",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:build_keycloak:"
          ],
          "defaultStatus": "affected",
          "product": "Red Hat Build of Keycloak",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:red_hat_single_sign_on:7"
          ],
          "defaultStatus": "affected",
          "product": "Red Hat Single Sign-On 7",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:cryostat:4"
          ],
          "defaultStatus": "unaffected",
          "product": "Cryostat 4",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:logging:5"
          ],
          "defaultStatus": "unaffected",
          "product": "Logging Subsystem for Red Hat OpenShift",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unaffected",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:acm:2"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat Advanced Cluster Management for Kubernetes 2",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:amq_broker:7"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat AMQ Broker 7",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:service_registry:2"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat build of Apicurio Registry 2",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:optaplanner:::el6"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat build of OptaPlanner 8",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:podman_desktop:1"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat Build of Podman Desktop",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:jboss_data_grid:8"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat Data Grid 8",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:directory_server:11"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat Directory Server 11",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:directory_server:12"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat Directory Server 12",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:directory_server:13"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat Directory Server 13",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:10"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat Enterprise Linux 10",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:8"
          ],
          "defaultStatus": "unaffected",
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          "vendor": "Red Hat"
        },
        {
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          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat Enterprise Linux 9",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:jboss_fuse:7"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat Fuse 7",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:7"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat JBoss Enterprise Application Platform 7",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:8"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat JBoss Enterprise Application Platform 8",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:jbosseapxp"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat JBoss Enterprise Application Platform Expansion Pack",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat OpenShift AI (RHOAI)",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift:4"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat OpenShift Container Platform 4",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_bpms_platform:7"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat Process Automation 7",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:quay:3"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat Quay 3",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
            "cpe:/a:redhat:amq_streams:2"
          ],
          "defaultStatus": "unaffected",
          "product": "streams for Apache Kafka 2",
          "vendor": "Red Hat"
        },
        {
          "cpes": [
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          ],
          "defaultStatus": "unaffected",
          "product": "streams for Apache Kafka 3",
          "vendor": "Red Hat"
        }
      ],
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:webreflection:flatted:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "B9B19945-5AD9-4557-A372-AF04A9EDC1BB",
              "versionEndExcluding": "3.4.2",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "flatted is a circular JSON parser. Prior to version 3.4.2, the parse() function in flatted can use attacker-controlled string values from the parsed JSON as direct array index keys, without validating that they are numeric. Since the internal input buffer is a JavaScript Array, accessing it with the key \"__proto__\" returns Array.prototype via the inherited getter. This object is then treated as a legitimate parsed value and assigned as a property of the output object, effectively leaking a live reference to Array.prototype to the consumer. Any code that subsequently writes to that property will pollute the global prototype. This issue has been patched in version 3.4.2."
    },
    {
      "lang": "es",
      "value": "flatted es un analizador de JSON circular. Antes de la versi\u00f3n 3.4.2, la funci\u00f3n parse() en flatted puede usar valores de cadena controlados por el atacante del JSON analizado como claves de \u00edndice de array directas, sin validar que sean num\u00e9ricos. Dado que el b\u00fafer de entrada interno es un Array de JavaScript, acceder a \u00e9l con la clave \u0027__proto__\u0027 devuelve Array.prototype a trav\u00e9s del getter heredado. Este objeto es entonces tratado como un valor analizado leg\u00edtimo y asignado como una propiedad del objeto de salida, filtrando efectivamente una referencia en vivo a Array.prototype al consumidor. Cualquier c\u00f3digo que posteriormente escriba en esa propiedad contaminar\u00e1 el prototipo global. Este problema ha sido parcheado en la versi\u00f3n 3.4.2."
    }
  ],
  "id": "CVE-2026-33228",
  "lastModified": "2026-06-27T05:16:43.903",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
        "type": "Secondary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 8.9,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "PROOF_OF_CONCEPT",
          "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": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/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": "HIGH",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
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    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
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          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-03-24T17:35:34.197834Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-03-20T23:16:46.510",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
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      "url": "https://github.com/WebReflection/flatted/commit/885ddcc33cf9657caf38c57c7be45ae1c5272802"
    },
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      "tags": [
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      "url": "https://github.com/WebReflection/flatted/releases/tag/v3.4.2"
    },
    {
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      "tags": [
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        "Vendor Advisory"
      ],
      "url": "https://github.com/WebReflection/flatted/security/advisories/GHSA-rf6f-7fwh-wjgh"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://access.redhat.com/errata/RHSA-2026:13826"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://access.redhat.com/errata/RHSA-2026:9742"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://access.redhat.com/security/cve/CVE-2026-33228"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2449872"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33228.json"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-1321"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-915"
        }
      ],
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "type": "Secondary"
    }
  ]
}


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Sightings

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  • 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.
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Detection rules are retrieved from Rulezet.