Square Squash through commit e73f280 Unauthenticated YAML Deserialization via Symbolication API

{
  "id": "04c8da24f749502111d117b0d8f8e8ea4357dd3ab4559e5ab1fc8a7c469bfa27",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-109391",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Square Squash through commit e73f280 Unauthenticated YAML Deserialization via Symbolication API",
    "summary": "Square Squash through commit e73f280 contains an insecure deserialization vulnerability that allows unauthenticated attackers to store crafted YAML via the POST /api/1.0/symbolication endpoint. When occurrences referencing the attacker-controlled symbolication UUID are symbolicated, the stored values are passed to YAML.load with SafeYAML in unsafe mode, enabling arbitrary Ruby object deserialization and potential code execution.",
    "evidence": "cve:CVE-2026-109391",
    "products": [
      {
        "name": {
          "value": "Squash",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-109391",
      "aliases": [
        "CVE-2026-109391"
      ],
      "metrics": [
        {
          "format": "CVSS",
          "cvssV4_0": {
            "version": "4.0",
            "baseScore": 9.2,
            "attackVector": "NETWORK",
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
            "userInteraction": "NONE",
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
            "privilegesRequired": "NONE",
            "subIntegrityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH",
            "subAvailabilityImpact": "NONE",
            "vulnAvailabilityImpact": "HIGH",
            "subConfidentialityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH"
          }
        },
        {
          "format": "CVSS",
          "cvssV3_1": {
            "scope": "UNCHANGED",
            "version": "3.1",
            "baseScore": 8.1,
            "attackVector": "NETWORK",
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "integrityImpact": "HIGH",
            "userInteraction": "NONE",
            "attackComplexity": "HIGH",
            "availabilityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "confidentialityImpact": "HIGH"
          }
        }
      ],
      "affected": [
        {
          "repo": "https://github.com/SquareSquash/web",
          "vendor": "Square",
          "product": "Squash",
          "versions": [
            {
              "status": "affected",
              "version": "0",
              "versionType": "git",
              "lessThanOrEqual": "e73f2805f9eb30780a5c213b001f0f4255660fbf"
            }
          ],
          "packageURL": "pkg:github/SquareSquash/web",
          "defaultStatus": "unaffected"
        }
      ],
      "modified": "2026-10-27T01:30:40.899Z",
      "provider": "cve",
      "references": [
        "https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/HJ87QX5ifg",
        "https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/app/controllers/api/v1_controller.rb",
        "https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/config/preinitializers/safe_yaml.rb",
        "https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/lib/workers/symbolication_creator.rb",
        "https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/app/models/symbolication.rb",
        "https://github.com/SquareSquash/web",
        "https://www.vulncheck.com/advisories/square-squash-through-commit-e73f280-unauthenticated-yaml-deserialization-via-symbolication-api"
      ],
      "provider_metadata": {
        "adp": [
          {
            "title": "CISA ADP Vulnrichment",
            "metrics": [
              {
                "other": {
                  "type": "ssvc",
                  "content": {
                    "id": "CVE-2026-109391",
                    "role": "CISA Coordinator",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "total"
                      }
                    ],
                    "version": "2.0.3",
                    "timestamp": "2026-10-13T16:40:50.798651Z"
                  }
                }
              }
            ],
            "providerMetadata": {
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP",
              "dateUpdated": "2026-10-13T16:57:23.986Z"
            }
          }
        ],
        "cna": {
          "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
          "shortName": "VulnCheck",
          "dateUpdated": "2026-10-27T01:30:40.899Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-109391",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/containers/cna/metrics"
  },
  "source_id": "core-cve",
  "document_id": 374638,
  "published_at": "2026-10-12T15:16:39.257+00:00"
}