Cotonti 1.0.0 Comments Plugin PHP Object Injection via ci Parameter

{
  "id": "a85813c202292618938b664148ad62b2c1ed43836a1b1a05a5f69e56fdcee6a9",
  "url": "https://osv.dev/vulnerability/CVE-2026-91939",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Cotonti 1.0.0 Comments Plugin PHP Object Injection via ci Parameter",
    "summary": "Cotonti 1.0.0 Comments plugin passes the ci GET parameter to unserialize() without allowed_classes restriction, allowing unauthenticated attackers to instantiate arbitrary PHP classes with attacker-controlled properties. Attackers can exploit PHP object injection through crafted serialized payloads to trigger gadget chains and achieve database manipulation or code execution.",
    "evidence": "osv:CVE-2026-91939",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-91939",
      "aliases": [
        "CVE-2026-91939"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/cotonti/cotonti",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0d554e939a315e7f7f18fba3ca1132b80c6a1adb"
                },
                {
                  "last_affected": "0d554e939a315e7f7f18fba3ca1132b80c6a1adb"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "1.0.0"
                      },
                      {
                        "last_affected": "1.0.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandaloneSingleVersion"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-91939.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:50.553581093Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91939.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-91939",
        "https://www.vulncheck.com/advisories/cotonti-1.0.0-comments-plugin-php-object-injection-via-ci-parameter",
        "https://github.com/Cotonti/Cotonti/issues/1888",
        "https://github.com/Cotonti/Cotonti/pull/1889",
        "https://github.com/Cotonti/Cotonti",
        "https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/comments/comments.setup.php",
        "https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/comments/controllers/actions/DisplayAction.php",
        "https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/comments/inc/CommentsWidget.php"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-502"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91939.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-91939",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 518924,
  "published_at": "2026-09-15T20:56:45.058+00:00"
}