# CVE-2026-126663: Contao path traversal in image insert tag

Source: https://junglewise.ai/threats/cve-2026-126663-contao-4-0-0-before-5-3-54-5-4-0-before-5-7-17-and-6-0-0-before  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-11. Updated: 2026-11-11  
License: CC BY 4.0 with a link back

CVE-2026-126663 · Severity: medium · CVSS 4.3 · Published 2026-11-11

Contao is a content management system used to build and manage web content. A path traversal vulnerability in the {{image::}} insert tag allows content editors to read arbitrary image files from the server's filesystem by bypassing validation with percent-encoded sequences, potentially exposing sensitive files outside the intended files directory.

Technologies: [Contao](https://junglewise.ai/threats/technologies/contao). Vendors: [Contao](https://junglewise.ai/threats/vendors/contao).

## Quick answers

**Is CVE-2026-126663 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-126663 being exploited in the wild.

**How severe is CVE-2026-126663?** Medium severity, with a CVSS score of 4.3, published 11 November 2026.

**Which products and versions are affected?** Contao 4.0.0 before 5.3.54, 5.4.0 before 5.7.17, 6.0.0 before 6.0.6.

**Is there a fix for CVE-2026-126663?** Yes: fixed in Contao 5.3.54, 5.7.17, 6.0.6. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-126663 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-126663?** Check whether you run Contao at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Contao 5.3.54, 5.7.17, 6.0.6

## Technical details

The vulnerability exists in the LegacyInsertTag image resolver, where path validation via Validator::isInsecurePath() is performed before URL decoding. An attacker with content editor privileges can embed percent-encoded path traversal sequences (e.g., ..%2f) that pass validation, then are decoded post-check, allowing the frontend resize handler to serve arbitrary readable image files. The fix applies rawurldecode() before validation to catch encoded traversal attempts.

## Affected products

- Contao Contao 4.0.0 before 5.3.54, 5.4.0 before 5.7.17, 6.0.0 before 6.0.6

## Timeline

- 2026-11-11: disclosed

## References

- [https://github.com/contao/contao/blob/5.3.53/core-bundle/src/InsertTag/Resolver/LegacyInsertTag.php](https://github.com/contao/contao/blob/5.3.53/core-bundle/src/InsertTag/Resolver/LegacyInsertTag.php)
- [https://github.com/contao/contao/commit/0f7989eb5b28d85dcd441ef22f80f8af4f56433e](https://github.com/contao/contao/commit/0f7989eb5b28d85dcd441ef22f80f8af4f56433e)

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