CVE-2026-126663 (CVSS 4.3)

Description

Contao 4.0.0 before 5.3.54, 5.4.0 before 5.7.17, and 6.0.0 before 6.0.6 contains a path traversal vulnerability that allows content editors to read image files anywhere on the filesystem via the {{image::}} insert tag. Attackers can embed percent-encoded sequences like ..%2f that pass Validator::isInsecurePath() before rawurldecode(), making the frontend resize and serve readable image files outside the files directory.

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CVSS v3.1 Score

4.3

MEDIUM

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

EPSS — Exploit Prediction

0.0036

Probability of exploitation

0.31%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-180 CWE-180

References

Other References

https://github.com/contao/contao/blob/5.3.53/core-bundle/src/InsertTag/Resolver/LegacyInsertTag.php#L565-L582 https://github.com/contao/contao/commit/0f7989eb5b28d85dcd441ef22f80f8af4f56433e https://github.com/contao/contao/commit/688c0f6213afbd000cd22ad0a44555eca80b40ab https://github.com/contao/contao/commit/e820e3c9d79a5c07f274558513c8db08a79bf804 https://github.com/contao/contao/releases/tag/5.3.54 https://github.com/contao/contao/releases/tag/5.7.17 https://github.com/contao/contao/releases/tag/6.0.6 https://github.com/contao/contao/security/advisories/GHSA-r7cf-mfp4-r23h https://www.vulncheck.com/advisories/contao-4.0.0-before-5.3.54-5.4.0-before-5.7.17-and-6.0.0-before-6.0.6-path-traversal-via-image-insert-tag

Frequently Asked Questions

What is CVE-2026-126663? +

Contao 4.0.0 before 5.3.54, 5.4.0 before 5.7.17, and 6.0.0 before 6.0.6 contains a path traversal vulnerability that allows content editors to read image files anywhere on the filesystem via the {{image::}} insert tag. Attackers can embed percent-encoded sequences like ..%2f that pass Validator::isInsecurePath() before rawurldecode(), making the frontend resize and serve readable image files outside the files directory. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-126663? +

CVE-2026-126663 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0036, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-126663? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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