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.

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

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. 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

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