GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2026-59725 (GCVE-0-2026-59725)

Vulnerability from cvelistv5 – Published: 2026-07-08 15:37 – Updated: 2026-07-08 17:00
VLAI
Title
Socket.IO: Engine.IO Polling Transport Connection Exhaustion
Summary
Socket.IO enables bidirectional and low-latency communication for every platform. From 4.1.0 before 6.6.7, Engine.IO protocol v4 polling transport does not properly close the HTTP response for invalid binary POST requests with Content-Type: application/octet-stream, allowing an unauthenticated attacker to exhaust server-side connections and sockets. This issue is fixed in version 6.6.7.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-08 16:50 UTC
CWE
  • CWE-404 - Improper Resource Shutdown or Release
Assigner
References
Impacted products
Vendor Product Version CPE status
socketio socket.io Affected: >= 4.1.0, < 6.6.7
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-59725",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-08T16:50:45.800976Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-08T17:00:32.946Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "socket.io",
          "vendor": "socketio",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.1.0, \u003c 6.6.7"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Socket.IO enables bidirectional and low-latency communication for every platform. From 4.1.0 before 6.6.7, Engine.IO protocol v4 polling transport does not properly close the HTTP response for invalid binary POST requests with Content-Type: application/octet-stream, allowing an unauthenticated attacker to exhaust server-side connections and sockets. This issue is fixed in version 6.6.7."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-404",
              "description": "CWE-404: Improper Resource Shutdown or Release",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-08T15:37:52.293Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/socketio/socket.io/security/advisories/GHSA-r635-g3xr-vw7x",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/socketio/socket.io/security/advisories/GHSA-r635-g3xr-vw7x"
        },
        {
          "name": "https://github.com/socketio/socket.io/commit/fc11285e14964c2132d122164bf130c355f60671",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/socketio/socket.io/commit/fc11285e14964c2132d122164bf130c355f60671"
        },
        {
          "name": "https://github.com/socketio/socket.io/releases/tag/engine.io@6.6.7",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/socketio/socket.io/releases/tag/engine.io@6.6.7"
        }
      ],
      "source": {
        "advisory": "GHSA-r635-g3xr-vw7x",
        "discovery": "UNKNOWN"
      },
      "title": "Socket.IO: Engine.IO Polling Transport Connection Exhaustion"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-59725",
    "datePublished": "2026-07-08T15:37:52.293Z",
    "dateReserved": "2026-07-06T15:34:16.916Z",
    "dateUpdated": "2026-07-08T17:00:32.946Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-59725",
      "date": "2026-09-20",
      "epss": "0.00636",
      "percentile": "0.49077"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "product": "socket.io",
                "vendor": "socketio",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003e= 4.1.0, \u003c 6.6.7"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:a:socket:engine.io:*:*:*:*:*:node.js:*:*",
                    "matchCriteriaId": "E891F735-E7C3-41E7-9B17-D0D3D2D6E299",
                    "versionEndExcluding": "6.6.7",
                    "versionStartIncluding": "4.1.0",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Socket.IO enables bidirectional and low-latency communication for every platform. From 4.1.0 before 6.6.7, Engine.IO protocol v4 polling transport does not properly close the HTTP response for invalid binary POST requests with Content-Type: application/octet-stream, allowing an unauthenticated attacker to exhaust server-side connections and sockets. This issue is fixed in version 6.6.7."
          }
        ],
        "id": "CVE-2026-59725",
        "lastModified": "2026-07-13T15:07:44.943",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 7.5,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 3.9,
              "impactScore": 3.6,
              "source": "security-advisories@github.com",
              "type": "Secondary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2026-59725",
                "options": [
                  {
                    "exploitation": "none"
                  },
                  {
                    "automatable": "yes"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-08T16:50:45.800976Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2026-07-08T16:16:33.133",
        "references": [
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Patch"
            ],
            "url": "https://github.com/socketio/socket.io/commit/fc11285e14964c2132d122164bf130c355f60671"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Release Notes"
            ],
            "url": "https://github.com/socketio/socket.io/releases/tag/engine.io@6.6.7"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Patch",
              "Vendor Advisory"
            ],
            "url": "https://github.com/socketio/socket.io/security/advisories/GHSA-r635-g3xr-vw7x"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Analyzed",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-404"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Secondary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-08-08T23:04:10+00:00",
      "cve": "CVE-2026-59725",
      "id": "CVE-2026-59725",
      "initial_release_date": "2026-07-08T15:37:52.293000+00:00",
      "product_status:fixed": "3",
      "product_status:known_affected": "4",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "socket.io: engine.io: Socket.IO: Denial of Service via invalid binary POST requests",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-59725.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2026-59725",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "yes"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-07-08T16:50:45.800976Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-07-08T16:50:49.427Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "product": "socket.io",
              "vendor": "socketio",
              "versions": [
                {
                  "status": "affected",
                  "version": "\u003e= 4.1.0, \u003c 6.6.7"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "Socket.IO enables bidirectional and low-latency communication for every platform. From 4.1.0 before 6.6.7, Engine.IO protocol v4 polling transport does not properly close the HTTP response for invalid binary POST requests with Content-Type: application/octet-stream, allowing an unauthenticated attacker to exhaust server-side connections and sockets. This issue is fixed in version 6.6.7."
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 7.5,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                "version": "3.1"
              }
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-404",
                  "description": "CWE-404: Improper Resource Shutdown or Release",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-07-08T15:37:52.293Z",
            "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
            "shortName": "GitHub_M"
          },
          "references": [
            {
              "name": "https://github.com/socketio/socket.io/security/advisories/GHSA-r635-g3xr-vw7x",
              "tags": [
                "x_refsource_CONFIRM"
              ],
              "url": "https://github.com/socketio/socket.io/security/advisories/GHSA-r635-g3xr-vw7x"
            },
            {
              "name": "https://github.com/socketio/socket.io/commit/fc11285e14964c2132d122164bf130c355f60671",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/socketio/socket.io/commit/fc11285e14964c2132d122164bf130c355f60671"
            },
            {
              "name": "https://github.com/socketio/socket.io/releases/tag/engine.io@6.6.7",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/socketio/socket.io/releases/tag/engine.io@6.6.7"
            }
          ],
          "source": {
            "advisory": "GHSA-r635-g3xr-vw7x",
            "discovery": "UNKNOWN"
          },
          "title": "Socket.IO: Engine.IO Polling Transport Connection Exhaustion"
        }
      },
      "cveMetadata": {
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "assignerShortName": "GitHub_M",
        "cveId": "CVE-2026-59725",
        "datePublished": "2026-07-08T15:37:52.293Z",
        "dateReserved": "2026-07-06T15:34:16.916Z",
        "dateUpdated": "2026-07-08T17:00:32.946Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.


Detection rules are retrieved from Rulezet.


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.