CVE-2026-75833

{
  "id": "CVE-2026-75833",
  "sourceIdentifier": "[email protected]",
  "published": "2026-08-18T12:19:33.370",
  "lastModified": "2026-10-22T22:10:00.250",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "The Grav API plugin (getgrav/grav-plugin-api, bundled with Grav 2.0's admin-next/API stack) before version 1.0.14 contains an open redirect weakness in SsoController::sanitizeReturnTo(). The function rejects a literal '//' prefix but does not account for browsers normalizing backslashes to slashes in special (http/https) schemes, so a returnTo value such as '/\\evil.com' passes the guard and is later resolved by the browser as the protocol-relative URL '//evil.com'. Following a legitimate OAuth login flow, an attacker-supplied returnTo parameter could redirect an authenticated victim to an attacker-controlled site for post-login phishing. Full browser-side exploitability depends on the admin-next SPA's client-side oauth-callback handler and was not independently verified by the reporter."
    },
    {
      "lang": "es",
      "value": "El plugin API de Grav (getgrav/grav-plugin-api, incluido con la pila admin-next/API de Grav 2.0) anterior a la versión 1.0.14 contiene una debilidad de redirección abierta en SsoController::sanitizeReturnTo(). La función rechaza un prefijo literal ’//’ pero no tiene en cuenta que los navegadores normalizan las barras invertidas a barras en esquemas especiales (HTTP/HTTPS), por lo que un valor returnTo como ’/\\evil.com’ pasa la protección y es posteriormente resuelto por el navegador como la URL relativa al protocolo ’//evil.com’. Tras un flujo de inicio de sesión OAuth legítimo, un parámetro returnTo proporcionado por el atacante podría redirigir a una víctima autenticada a un sitio controlado por el atacante para phishing posterior al inicio de sesión. La explotabilidad completa del lado del navegador depende del gestor oauth-callback del lado del cliente de la SPA admin-next y no fue verificada independientemente por el informante."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "getgrav",
          "product": "grav",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "0",
              "lessThan": "1.0.14",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "1.0.14",
              "versionType": "semver",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV40": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "4.0",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "baseScore": 8.6,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "privilegesRequired": "LOW",
          "userInteraction": "PASSIVE",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnAvailabilityImpact": "HIGH",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "subAvailabilityImpact": "NONE",
          "exploitMaturity": "NOT_DEFINED",
          "confidentialityRequirement": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "valueDensity": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N",
          "baseScore": 4.2,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "HIGH",
          "privilegesRequired": "NONE",
          "userInteraction": "REQUIRED",
          "scope": "UNCHANGED",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 1.6,
        "impactScore": 2.5
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-08-18T13:41:12.267567Z",
          "id": "CVE-2026-75833",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-601"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/getgrav/grav/security/advisories/GHSA-x72c-4jc4-8rh6",
      "source": "[email protected]"
    },
    {
      "url": "https://www.vulncheck.com/advisories/grav-api-plugin-open-redirect-via-backslash-bypass",
      "source": "[email protected]"
    }
  ]
}