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FKIE_CVE-2026-52767

Vulnerability from fkie_nvd - Published: 2026-09-05 00:17 - Updated: 2026-09-05 00:17
Severity
8.2 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
Summary
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.
References
security-advisories@github.comhttps://github.com/YesWiki/yeswiki/commit/d1795e0301e1a1078f17b4b98f56fff70de2029e
security-advisories@github.comhttps://github.com/YesWiki/yeswiki/releases/tag/v4.6.6
security-advisories@github.comhttps://github.com/YesWiki/yeswiki/security/advisories/GHSA-mv28-wj57-f57g
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "yeswiki",
          "vendor": "YesWiki",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.6.2, \u003c 4.6.6"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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\u0027s openssl_verify() with a loose boolean negation - if (!openssl_verify(...)) { throw ... }. PHP\u0027s openssl_verify has four possible return values: 1, 0, -1, and \"false\". The -1 row is the bypass: PHP\u0027s 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\u0027s EVP_VerifyFinal() return -1 triggers the bypass. The reachable consequence is the controller silently treats a failed verification as success and processes the attacker\u0027s payload. This issue has been patched in version 4.6.6."
    }
  ],
  "id": "CVE-2026-52767",
  "lastModified": "2026-09-05T00:17:19.540",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 8.2,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 4.2,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-05T00:17:19.540",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/YesWiki/yeswiki/commit/d1795e0301e1a1078f17b4b98f56fff70de2029e"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/YesWiki/yeswiki/security/advisories/GHSA-mv28-wj57-f57g"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-347"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}



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