{
  "id": "CVE-2026-52767",
  "url": "https://spydr.io/cve/CVE-2026-52767",
  "published": "2026-09-05T00:17:19.540Z",
  "modified": "2026-09-08T21:05:26.920Z",
  "score": 8.2,
  "severity": "high",
  "cvss_version": "3.1",
  "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L",
  "score_source": "github.com",
  "epss": 0.00352,
  "epss_percentile": 0.2661,
  "exploited": false,
  "kev": null,
  "ssvc_exploitation": "poc",
  "vendors": [
    "YesWiki"
  ],
  "products": [
    "yeswiki"
  ],
  "cwes": [
    "CWE-347"
  ],
  "description": "YesWiki is a wiki system written in PHP. From version 4.6.2 to before version 4.6.6, HttpSignatureService::verifySignature() checks the result of PHP's openssl_verify() with a loose boolean negation - if (!openssl_verify(...)) { throw ... }. PHP's openssl_verify has four possible return values: 1, 0, -1, and \"false\". The -1 row is the bypass: PHP's truthiness rules make -1 a truthy value, so !(-1) === false, the throw is skipped, and the controller proceeds to processActivity(). Any condition that makes OpenSSL's EVP_VerifyFinal() return -1 triggers the bypass. The reachable consequence is the controller silently treats a failed verification as success and processes the attacker's payload. This issue has been patched in version 4.6.6.",
  "status": "Deferred",
  "score_type": "Secondary",
  "scores": {
    "cvss_v40": null,
    "cvss_v31": 8.2,
    "cvss_v30": null
  },
  "references": [
    {
      "url": "https://github.com/YesWiki/yeswiki/commit/d1795e0301e1a1078f17b4b98f56fff70de2029e",
      "tags": []
    },
    {
      "url": "https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6",
      "tags": []
    },
    {
      "url": "https://github.com/YesWiki/yeswiki/security/advisories/GHSA-mv28-wj57-f57g",
      "tags": []
    }
  ],
  "nvd_url": "https://nvd.nist.gov/vuln/detail/CVE-2026-52767",
  "covered_in": [],
  "attribution": [
    {
      "source": "NVD",
      "url": "https://nvd.nist.gov",
      "notice": "This product uses data from the NVD API but is not endorsed or certified by the NVD."
    },
    {
      "source": "CISA KEV",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "notice": "Known exploited vulnerabilities from the CISA KEV catalog."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss",
      "notice": "Exploit prediction scores from FIRST EPSS."
    }
  ]
}