Vulnerability-Lookup

CVE-2026-55824 (GCVE-0-2026-55824)

Vulnerability from cvelistv5 – Published: 2026-07-31 19:04 – Updated: 2026-07-31 19:58

Title

Contao crawler leaks auth credentials to external hosts

Summary

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's 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's 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.

Severity

2.6 (Low)


                        
                          CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-31 19:58 UTC

CWE

CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor

Assigner

GitHub_M mitre root

References

1 reference

URL	Tags
https://github.com/contao/contao/security/advisor…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version	CPE status
contao	contao	Affected: >= 4.13.40, < 5.3.47 Affected: >= 5.7.0-RC1, < 5.7.7	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-55824

Vulnerability from fkie_nvd - Published: 2026-07-31 19:17 - Updated: 2026-09-08 20:51

Severity

2.6 (Low) - CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/contao/contao/security/advisories/GHSA-3mr9-p497-58f6

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "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": [],
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    {
      "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",
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GHSA-3MR9-P497-58F6

Vulnerability from github – Published: 2026-08-06 19:43 – Updated: 2026-08-06 19:43

Summary

Contao crawler leaks auth credentials to external hosts

Details

Summary

Contao's 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's 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.

Technical Detail

Root Cause

// core-bundle/src/Crawl/Escargot/Factory.php:175-209 @ e550b92a01ef625bd546e6c3956dd200af05ebf0
private function createHttpClient(array $options = []): HttpClientInterface
{
    $options = array_merge_recursive(
        [
            'headers' => [
                'accept' => 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
                'user-agent' => self::USER_AGENT,
            ],
            'max_duration' => 10,
        ],
        array_merge_recursive($this->getDefaultHttpClientOptions(), $options),
    );

    $cleanOptions = $this->cleanOptionsFromConfidentialData($options);

    if ($options === $cleanOptions) {
        return ($this->httpClientFactory)($options);
    }

    $scopedOptionsByRegex = [];

    foreach ($this->getRootPageUriCollection()->all() as $rootPageUri) {
        $scopedOptionsByRegex[preg_quote($this->getOriginFromUri($rootPageUri))] = $options;
    }

    return new ScopingHttpClient(($this->httpClientFactory)($cleanOptions), $scopedOptionsByRegex);
}

// core-bundle/src/Crawl/Escargot/Factory.php:226-247 @ e550b92a01ef625bd546e6c3956dd200af05ebf0
foreach ($options as $k => $v) {
    if ('headers' === $k) {
        foreach ($v as $header => $value) {
            if (\in_array(strtolower($header), ['authorization', 'cookie'], true)) {
                continue;
            }

            $cleanOptions['headers'][$header] = $value;
        }

        continue;
    }

    if ('basic_auth' === $k || 'bearer_auth' === $k) {
        continue;
    }

    $cleanOptions[$k] = $v;
}

Symfony HttpClient authentication options are auth_basic and auth_bearer; Contao's 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).

Suggested Mitigation

Strip 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.

-            if ('basic_auth' === $k || 'bearer_auth' === $k) {
+            if (\in_array($k, ['auth_basic', 'auth_bearer', 'auth_ntlm', 'basic_auth', 'bearer_auth'], true)) {
                 continue;
             }

Also 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.

Impact

Direct primitive: disclosure of crawler Basic/Bearer credentials to an external host reached by the crawler.
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.
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.

Severity

2.6 (Low)


                  
                    CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N

Show details on source website

JSON

To clipboard

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        "name": "contao/contao"
      },
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      "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"
}

WID-SEC-W-2026-1921

Vulnerability from csaf_certbund - Published: 2026-06-14 22:00 - Updated: 2026-08-02 22:00

Summary

Contao: Mehrere Schwachstellen ermöglichen Offenlegung von Informationen

Severity

Niedrig

Scope

2 vulnerabilities in this advisory, including CVE-2026-55824.

CVE-2026-55824

Known affected: 2 products

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-55824 (GCVE-0-2026-55824)

FKIE_CVE-2026-55824

GHSA-3MR9-P497-58F6

Summary

Technical Detail

Root Cause

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Impact

WID-SEC-W-2026-1921

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