CVE-2026-55824

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.

• CWE-200

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

Published

Jul 31, 2026

Last Modified

Jul 31, 2026

Status

Received

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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