Security advisory

{
  "id": "8ab3113b072fed87cf2ae9767d1f2a669cfb247f41408b3b0a6b819144f929f1",
  "url": "https://osv.dev/vulnerability/CVE-2021-41556",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-41556",
    "summary": "sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bounds read (in the core interpreter) that can lead to Code Execution. If a victim executes an attacker-controlled squirrel script, it is possible for the attacker to break out of the squirrel script sandbox even if all dangerous functionality such as File System functions has been disabled. An attacker might abuse this bug to target (for example) Cloud services that allow customization via SquirrelScripts, or distribute malware through video games that embed a Squirrel Engine.",
    "evidence": "osv:CVE-2021-41556",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2021-41556",
      "aliases": [
        "CVE-2021-41556"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/albertodemichelis/squirrel",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "c52b25d864400197fa4d64c46254d8b1de06c2fa"
                },
                {
                  "fixed": "23a0620658714b996d20da3d4dd1a0dcf9b0bd98"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:squirrel-lang:squirrel:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "3.0"
                      },
                      {
                        "last_affected": "3.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "23a0620658714b996d20da3d4dd1a0dcf9b0bd98"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v3.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-41556.json",
            "vanir_signatures": [
              {
                "id": "CVE-2021-41556-7378500a",
                "digest": {
                  "length": 1327,
                  "function_hash": "218714802154936925267298589577355166457"
                },
                "source": "https://github.com/albertodemichelis/squirrel/commit/23a0620658714b996d20da3d4dd1a0dcf9b0bd98",
                "target": {
                  "file": "squirrel/sqclass.cpp",
                  "function": "SQClass::NewSlot"
                },
                "deprecated": false,
                "signature_type": "Function",
                "signature_version": "v1"
              },
              {
                "id": "CVE-2021-41556-ed2333f9",
                "digest": {
                  "threshold": 0.9,
                  "line_hashes": [
                    "92675059631009288048213461542740346520",
                    "296186921292990067100642253571993597728",
                    "40872597398596125545265975713465823595",
                    "178672236382474547461178361631356191776"
                  ]
                },
                "source": "https://github.com/albertodemichelis/squirrel/commit/23a0620658714b996d20da3d4dd1a0dcf9b0bd98",
                "target": {
                  "file": "squirrel/sqclass.cpp"
                },
                "deprecated": false,
                "signature_type": "Line",
                "signature_version": "v1"
              }
            ],
            "vanir_signatures_modified": "2026-10-20T14:06:42Z"
          }
        }
      ],
      "modified": "2026-10-20T14:06:42.626352619Z",
      "provider": "osv",
      "references": [
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BV7SJJ44AGAX4ILIVPREIXPJ2GOG3FKV/",
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M3FQILX7UUEERSDPMZP3MKGTMY2E7ESU/",
        "https://github.com/albertodemichelis/squirrel/commit/23a0620658714b996d20da3d4dd1a0dcf9b0bd98",
        "https://www.sonarsource.com/blog/squirrel-vm-sandbox-escape/",
        "https://blog.sonarsource.com/squirrel-vm-sandbox-escape/"
      ],
      "provider_metadata": {
        "unresolved_ranges": [
          {
            "cpes": [
              "cpe:2.3:a:squirrel-lang:squirrel:*:*:*:*:*:*:*:*"
            ],
            "vendor_product": "squirrel-lang:squirrel",
            "extracted_events": [
              {
                "range": [
                  {
                    "last_affected": "2.2.5"
                  }
                ],
                "source": "CPE_RANGE"
              }
            ]
          },
          {
            "cpes": [
              "cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*",
              "cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:*"
            ],
            "vendor_product": "fedoraproject:fedora",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "35"
                  },
                  {
                    "last_affected": "35"
                  },
                  {
                    "introduced": "36"
                  },
                  {
                    "last_affected": "36"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          }
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2021-41556",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 388563,
  "published_at": "2022-07-28T21:15:08.057+00:00"
}