Cypht < 2.12.2 PHP Object Injection RCE via back_query Parameter

{
  "id": "7f29e2e7ccb3b444aaae19f5fb1b8a80be7a491e0e2726a8c97e42ffcb6624c3",
  "url": "https://osv.dev/vulnerability/CVE-2026-71981",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Cypht < 2.12.2 PHP Object Injection RCE via back_query Parameter",
    "summary": "Cypht before 2.12.2 contains a PHP object injection vulnerability that allows authenticated attackers to execute arbitrary operating system commands by supplying a crafted PHP object graph in the back_query GET parameter of the logout handler. Attackers can pass a base64-encoded serialized payload through this parameter, which is decoded and passed directly to unserialize() without an allow-list, signature check, or type restriction, enabling gadget-chain exploitation to achieve remote code execution as the web server process.",
    "evidence": "osv:CVE-2026-71981",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-71981",
      "aliases": [
        "CVE-2026-71981"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/cypht-org/cypht",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "fbaf979c3740a6e0f72e3a6c96e4a5102aae2133"
                },
                {
                  "fixed": "e4aa2f34e33f9328e8c93514cc3966fc3d99925e"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.12.2"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "fbaf979c3740a6e0f72e3a6c96e4a5102aae2133"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v2.12.2"
                  },
                  {
                    "range": [
                      {
                        "fixed": "e4aa2f34e33f9328e8c93514cc3966fc3d99925e"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.12.0",
            "v2.11.0",
            "v2.5.0",
            "v2.2.0",
            "v2.1.0",
            "v2.0.1",
            "v2.0.0",
            "v1.3.0-rc1",
            "v1.1.0-rc1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-71981.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:26.079302130Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/71xxx/CVE-2026-71981.json",
        "https://github.com/cypht-org/cypht/releases/tag/v2.12.2",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-71981",
        "https://www.vulncheck.com/advisories/cypht-php-object-injection-rce-via-back-query-parameter",
        "https://github.com/cypht-org/cypht/pull/2073",
        "https://github.com/cypht-org/cypht/commit/e4aa2f34e33f9328e8c93514cc3966fc3d99925e",
        "https://github.com/cypht-org/cypht"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-502"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/71xxx/CVE-2026-71981.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-71981",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 492468,
  "published_at": "2026-09-01T20:43:08.844+00:00"
}