{
  "affected": [
    {
      "affectedData": [
        {
          "product": "contao",
          "vendor": "contao",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.13.40, \u003c 5.3.47"
            },
            {
              "status": "affected",
              "version": "\u003e= 5.7.0-RC1, \u003c 5.7.7"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Contao is an Open Source CMS. In versions 4.13.40 through 5.3.46 and 5.7.0-RC1 through 5.7.6, the crawler leaks auth credentials to external hosts. Contao\u0027s crawler tries to prevent confidential HTTP client options from being sent to external domains by creating a scoped client: full options for root page origins, cleaned options for everything else. The cleaner removes Cookie and Authorization headers, but it removes the non-Symfony option names basic_auth and bearer_auth instead of Symfony HttpClient\u0027s real auth_basic and auth_bearer options. When contao.crawl.default_http_client_options contains Basic or Bearer authentication for a protected staging/production site, those credentials remain in the \"clean\" client used for external links or configured additional URIs. An attacker who can get an external URL crawled, for example through a link on a crawled page while the broken-link checker is enabled, can receive the crawler credentials. This issue has been fixed in versions 5.3.47 and 5.7.7."
    }
  ],
  "id": "CVE-2026-55824",
  "lastModified": "2026-09-08T20:51:43.490",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 2.6,
          "baseSeverity": "LOW",
          "confidentialityImpact": "LOW",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 1.2,
        "impactScore": 1.4,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-55824",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-07-31T19:58:23.916842Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-31T19:17:11.090",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/contao/contao/security/advisories/GHSA-3mr9-p497-58f6"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-200"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "contao/contao"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.13.0"
            },
            {
              "fixed": "5.3.47"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "contao/contao"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.4.0"
            },
            {
              "fixed": "5.7.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "contao/core-bundle"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.13.0"
            },
            {
              "fixed": "5.3.47"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "contao/core-bundle"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.4.0"
            },
            {
              "fixed": "5.7.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55824"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-200"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-06T19:43:02Z",
    "nvd_published_at": "2026-07-31T19:17:11Z",
    "severity": "LOW"
  },
  "details": "### Summary\nContao\u0027s crawler tries to prevent confidential HTTP client options from being sent to external domains by creating a scoped client: full options for root page origins, cleaned options for everything else. The cleaner removes `Cookie` and `Authorization` headers, but it removes the non-Symfony option names `basic_auth` and `bearer_auth` instead of Symfony HttpClient\u0027s real `auth_basic` and `auth_bearer` options.\n\nWhen `contao.crawl.default_http_client_options` contains Basic or Bearer authentication for a protected staging/production site, those credentials remain in the \"clean\" client used for external links or configured additional URIs. An attacker who can get an external URL crawled, for example through a link on a crawled page while the broken-link checker is enabled, can receive the crawler credentials.\n\n## Technical Detail\n\n### Root Cause\n\n```php\n// core-bundle/src/Crawl/Escargot/Factory.php:175-209 @ e550b92a01ef625bd546e6c3956dd200af05ebf0\nprivate function createHttpClient(array $options = []): HttpClientInterface\n{\n    $options = array_merge_recursive(\n        [\n            \u0027headers\u0027 =\u003e [\n                \u0027accept\u0027 =\u003e \u0027text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\u0027,\n                \u0027user-agent\u0027 =\u003e self::USER_AGENT,\n            ],\n            \u0027max_duration\u0027 =\u003e 10,\n        ],\n        array_merge_recursive($this-\u003egetDefaultHttpClientOptions(), $options),\n    );\n\n    $cleanOptions = $this-\u003ecleanOptionsFromConfidentialData($options);\n\n    if ($options === $cleanOptions) {\n        return ($this-\u003ehttpClientFactory)($options);\n    }\n\n    $scopedOptionsByRegex = [];\n\n    foreach ($this-\u003egetRootPageUriCollection()-\u003eall() as $rootPageUri) {\n        $scopedOptionsByRegex[preg_quote($this-\u003egetOriginFromUri($rootPageUri))] = $options;\n    }\n\n    return new ScopingHttpClient(($this-\u003ehttpClientFactory)($cleanOptions), $scopedOptionsByRegex);\n}\n```\n\n```php\n// core-bundle/src/Crawl/Escargot/Factory.php:226-247 @ e550b92a01ef625bd546e6c3956dd200af05ebf0\nforeach ($options as $k =\u003e $v) {\n    if (\u0027headers\u0027 === $k) {\n        foreach ($v as $header =\u003e $value) {\n            if (\\in_array(strtolower($header), [\u0027authorization\u0027, \u0027cookie\u0027], true)) {\n                continue;\n            }\n\n            $cleanOptions[\u0027headers\u0027][$header] = $value;\n        }\n\n        continue;\n    }\n\n    if (\u0027basic_auth\u0027 === $k || \u0027bearer_auth\u0027 === $k) {\n        continue;\n    }\n\n    $cleanOptions[$k] = $v;\n}\n```\n\nSymfony HttpClient authentication options are `auth_basic` and `auth_bearer`; Contao\u0027s own manual documents `auth_basic` for crawler Basic Authentication. Because the cleaner only strips `basic_auth` and `bearer_auth`, the \"clean\" default client for non-root-page hosts still carries the real auth options. The existing factory test intends to assert that `Authorization` is not sent to `www.foreign-domain.com`, but its mock client factory ignores the `$defaultOptions` argument, so it does not catch auth options that survive into `HttpClient::create($cleanOptions)`.\n\n\n## Suggested Mitigation\n\nStrip the actual Symfony HttpClient authentication option keys from the clean client. Include NTLM as a defensive extension because Symfony documents it as another auth option.\n\n```diff\n-            if (\u0027basic_auth\u0027 === $k || \u0027bearer_auth\u0027 === $k) {\n+            if (\\in_array($k, [\u0027auth_basic\u0027, \u0027auth_bearer\u0027, \u0027auth_ntlm\u0027, \u0027basic_auth\u0027, \u0027bearer_auth\u0027], true)) {\n                 continue;\n             }\n```\n\nAlso update the factory test so the mock factory records or preserves `$defaultOptions`; otherwise the test does not verify what `HttpClient::create($cleanOptions)` receives in production.\n\n## Impact\n\n- **Direct primitive**: disclosure of crawler Basic/Bearer credentials to an external host reached by the crawler.\n- **Chain potential**: if those credentials protect a staging or pre-publication environment, an attacker can use them to access that environment. The impact depends on what the leaked credential unlocks.\n- **Realistic exploitation**: a content editor adds a link to `https://attacker.example/probe` on a page that the crawler visits. When an administrator or scheduled maintenance run starts the broken-link checker with crawler Basic/Bearer authentication configured, the request to the attacker URL includes the generated `Authorization` header.",
  "id": "GHSA-3mr9-p497-58f6",
  "modified": "2026-08-06T19:43:02Z",
  "published": "2026-08-06T19:43:02Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/contao/contao/security/advisories/GHSA-3mr9-p497-58f6"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55824"
    },
    {
      "type": "WEB",
      "url": "https://github.com/contao/contao/commit/5bc6e3f900c439313df57aa561d0865792aafa05"
    },
    {
      "type": "WEB",
      "url": "https://github.com/contao/contao/commit/80425d28cdf66280a209bd3f5bc31b1a76901a04"
    },
    {
      "type": "WEB",
      "url": "https://contao.org/en/security-advisories/credentials-disclosure-in-the-crawler"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/contao/contao/CVE-2026-55824.yaml"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/contao/core-bundle/CVE-2026-55824.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/contao/contao"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Contao crawler leaks auth credentials to external hosts"
}