« Volver al listado

CVE-2026-56812

Estado: ModificadaMedia (6.3)—

Improper Check for Unusual or Exceptional Conditions vulnerability in phoenixframework phoenix (Presence JavaScript client) allows an attacker with ordinary channel access to cause a persistent client-side denial of service against every viewer of a presence channel topic.

This vulnerability is associated with program files assets/js/phoenix/presence.js and program routines Presence.syncState and Presence.syncDiff.

The Phoenix JavaScript presence client checks whether a presence already exists with a bare truthiness test (state[key]) instead of an own-property check.

Leer descripción completaMostrar menos

Presence keys can be attacker-controlled, because applications track presences under a username or id supplied by the client. A user who joins a channel choosing a key that is an Object.prototype member name (__proto__, constructor, toString, hasOwnProperty, and similar) makes that lookup return JavaScript's built-in Object.prototype instead of undefined. Because the prototype is truthy, the code treats it as an existing presence and reads .metas.map(...) off it, which throws an uncaught TypeError.

The exception propagates out of the presence message handler, so the local state is never updated and onSync() never fires. Because the malicious key is tracked on the server, it is re-pushed on every presence update and keeps re-throwing, so presence sync stays broken for every viewer of that channel topic until the attacker leaves. Both syncState and syncDiff use the same unsafe existence-check pattern. The impact is limited to the affected topic and is a read-time confusion of the prototype object, not a mutation of Object.prototype (it is not prototype pollution).

This issue affects phoenix: from 1.2.0-rc.0 before 1.5.15, from 1.6.0-rc.0 before 1.6.17, from 1.7.0-rc.0 before 1.7.24, and from 1.8.0-rc.0 before 1.8.9; phoenix: from 1.2.0-rc.0 before 1.5.15, from 1.6.0-rc.0 before 1.6.17, from 1.7.0-rc.0 before 1.7.24, and from 1.8.0-rc.0 before 1.8.9.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Phoenixframework — Phoenix

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-56812",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-56812",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-07-07T16:11:03.353715Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ],
    "cvssMetricV40": [
      {
        "type": "Secondary",
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 6.3,
          "Automatable": "NOT_DEFINED",
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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",
          "exploitMaturity": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "privilegesRequired": "NONE",
          "subIntegrityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "vulnAvailabilityImpact": "LOW",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "subConfidentialityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
        }
      }
    ]
  },
  "affected": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "affectedData": [
        {
          "cpes": [
            "cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*"
          ],
          "repo": "https://github.com/phoenixframework/phoenix",
          "vendor": "phoenixframework",
          "modules": [
            "Presence"
          ],
          "product": "phoenix",
          "versions": [
            {
              "status": "affected",
              "version": "1.2.0-rc.0",
              "lessThan": "1.5.15",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "1.6.0-rc.0",
              "lessThan": "1.6.17",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "1.7.0-rc.0",
              "lessThan": "1.7.24",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "1.8.0-rc.0",
              "lessThan": "1.8.9",
              "versionType": "semver"
            }
          ],
          "packageURL": "pkg:hex/phoenix",
          "packageName": "phoenix",
          "programFiles": [
            "assets/js/phoenix/presence.js"
          ],
          "collectionURL": "https://repo.hex.pm",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "Presence.syncState"
            },
            {
              "name": "Presence.syncDiff"
            }
          ]
        },
        {
          "cpes": [
            "cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*"
          ],
          "repo": "https://github.com/phoenixframework/phoenix",
          "vendor": "phoenixframework",
          "modules": [
            "Presence"
          ],
          "product": "phoenix",
          "versions": [
            {
              "status": "affected",
              "version": "1.2.0-rc.0",
              "lessThan": "1.5.15",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "1.6.0-rc.0",
              "lessThan": "1.6.17",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "1.7.0-rc.0",
              "lessThan": "1.7.24",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "1.8.0-rc.0",
              "lessThan": "1.8.9",
              "versionType": "semver"
            }
          ],
          "packageURL": "pkg:npm/phoenix",
          "packageName": "phoenix",
          "programFiles": [
            "assets/js/phoenix/presence.js"
          ],
          "collectionURL": "https://registry.npmjs.org",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "Presence.syncState"
            },
            {
              "name": "Presence.syncDiff"
            }
          ]
        },
        {
          "cpes": [
            "cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*"
          ],
          "repo": "https://github.com/phoenixframework/phoenix",
          "vendor": "phoenixframework",
          "modules": [
            "Presence"
          ],
          "product": "phoenix",
          "versions": [
            {
              "status": "affected",
              "changes": [
                {
                  "at": "7f7b971c1ea0994e3fbd1c11ddb05e780bd38ad8",
                  "status": "unaffected"
                },
                {
                  "at": "89a1c4be161e436241e12b2378a719904b9bd96f",
                  "status": "unaffected"
                },
                {
                  "at": "b90b22521465ece00eb5a19d5aa2b9465b209c85",
                  "status": "unaffected"
                },
                {
                  "at": "beffc4da1e787e572121f68902c63daf4fe7d9c2",
                  "status": "unaffected"
                }
              ],
              "version": "2270aaf21bd02c6a6a1022820564efb605a97655",
              "lessThan": "*",
              "versionType": "git"
            }
          ],
          "packageURL": "pkg:github/phoenixframework/phoenix",
          "packageName": "phoenixframework/phoenix",
          "programFiles": [
            "assets/js/phoenix/presence.js"
          ],
          "collectionURL": "https://github.com",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "Presence.syncState"
            },
            {
              "name": "Presence.syncDiff"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-07-07T16:16:40.920",
  "references": [
    {
      "url": "https://cna.erlef.org/cves/CVE-2026-56812.html",
      "tags": [
        "Mitigation",
        "Patch",
        "Third Party Advisory"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/phoenixframework/phoenix/commit/2270aaf21bd02c6a6a1022820564efb605a97655",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/phoenixframework/phoenix/commit/7f7b971c1ea0994e3fbd1c11ddb05e780bd38ad8",
      "tags": [
        "Patch"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/phoenixframework/phoenix/commit/89a1c4be161e436241e12b2378a719904b9bd96f",
      "tags": [
        "Patch"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/phoenixframework/phoenix/commit/b90b22521465ece00eb5a19d5aa2b9465b209c85",
      "tags": [
        "Patch"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/phoenixframework/phoenix/commit/beffc4da1e787e572121f68902c63daf4fe7d9c2",
      "tags": [
        "Patch"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/phoenixframework/phoenix/security/advisories/GHSA-63mc-hw7g-86rr",
      "tags": [
        "Exploit",
        "Patch",
        "Vendor Advisory"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-56812",
      "tags": [
        "Mitigation",
        "Third Party Advisory"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/phoenixframework/phoenix/security/advisories/GHSA-63mc-hw7g-86rr",
      "tags": [
        "Exploit",
        "Patch",
        "Vendor Advisory"
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "description": [
        {
          "lang": "en",
          "value": "CWE-754"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Improper Check for Unusual or Exceptional Conditions vulnerability in phoenixframework phoenix (Presence JavaScript client) allows an attacker with ordinary channel access to cause a persistent client-side denial of service against every viewer of a presence channel topic.\n\nThis vulnerability is associated with program files assets/js/phoenix/presence.js and program routines Presence.syncState and Presence.syncDiff.\n\nThe Phoenix JavaScript presence client checks whether a presence already exists with a bare truthiness test (state[key]) instead of an own-property check. Presence keys can be attacker-controlled, because applications track presences under a username or id supplied by the client. A user who joins a channel choosing a key that is an Object.prototype member name (__proto__, constructor, toString, hasOwnProperty, and similar) makes that lookup return JavaScript's built-in Object.prototype instead of undefined. Because the prototype is truthy, the code treats it as an existing presence and reads .metas.map(...) off it, which throws an uncaught TypeError.\n\nThe exception propagates out of the presence message handler, so the local state is never updated and onSync() never fires. Because the malicious key is tracked on the server, it is re-pushed on every presence update and keeps re-throwing, so presence sync stays broken for every viewer of that channel topic until the attacker leaves. Both syncState and syncDiff use the same unsafe existence-check pattern. The impact is limited to the affected topic and is a read-time confusion of the prototype object, not a mutation of Object.prototype (it is not prototype pollution).\n\nThis issue affects phoenix: from 1.2.0-rc.0 before 1.5.15, from 1.6.0-rc.0 before 1.6.17, from 1.7.0-rc.0 before 1.7.24, and from 1.8.0-rc.0 before 1.8.9; phoenix: from 1.2.0-rc.0 before 1.5.15, from 1.6.0-rc.0 before 1.6.17, from 1.7.0-rc.0 before 1.7.24, and from 1.8.0-rc.0 before 1.8.9."
    }
  ],
  "lastModified": "2026-09-24T22:17:00.683",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "3CF8EA55-C063-4742-87ED-53E1998977B5",
              "versionEndExcluding": "1.5.15",
              "versionStartIncluding": "1.2.0"
            },
            {
              "criteria": "cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "809E49A8-D727-4E05-BBF9-F9E34077E4A4",
              "versionEndExcluding": "1.6.17",
              "versionStartIncluding": "1.6.0"
            },
            {
              "criteria": "cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "3257C901-8FC3-4107-95C6-C57F909FFE40",
              "versionEndExcluding": "1.7.24",
              "versionStartIncluding": "1.7.0"
            },
            {
              "criteria": "cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "8F98C1AC-1593-43EB-929A-4D3B7597C9BC",
              "versionEndExcluding": "1.8.9",
              "versionStartIncluding": "1.8.0"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}