Contao up to 5.3.53/5.7.16/6.0.5 Insert Tag isInsecurePath path traversal

Summaryinfo

A vulnerability identified as problematic has been detected in Contao up to 5.3.53/5.7.16/6.0.5. This vulnerability affects the function Validator::isInsecurePath of the component Insert Tag. Performing a manipulation results in path traversal. This vulnerability is identified as CVE-2026-126663. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Contao up to 5.3.53/5.7.16/6.0.5. This affects the function Validator::isInsecurePath of the component Insert Tag. The manipulation with an unknown input leads to a path traversal vulnerability. CWE is classifying the issue as CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. This is going to have an impact on confidentiality. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-126663 since 11/11/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1006 for this issue.

Upgrading to version 5.3.54, 5.7.17 or 6.0.6 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• Contao

Version

• 5.3.0
• 5.3.1
• 5.3.2
• 5.3.3
• 5.3.4
• 5.3.5
• 5.3.6
• 5.3.7
• 5.3.8
• 5.3.9
• 5.3.10
• 5.3.11
• 5.3.12
• 5.3.13
• 5.3.14
• 5.3.15
• 5.3.16
• 5.3.17
• 5.3.18
• 5.3.19
• 5.3.20
• 5.3.21
• 5.3.22
• 5.3.23
• 5.3.24
• 5.3.25
• 5.3.26
• 5.3.27
• 5.3.28
• 5.3.29
• 5.3.30
• 5.3.31
• 5.3.32
• 5.3.33
• 5.3.34
• 5.3.35
• 5.3.36
• 5.3.37
• 5.3.38
• 5.3.39
• 5.3.40
• 5.3.41
• 5.3.42
• 5.3.43
• 5.3.44
• 5.3.45
• 5.3.46
• 5.3.47
• 5.3.48
• 5.3.49
• 5.3.50
• 5.3.51
• 5.3.52
• 5.3.53
• 5.7.0
• 5.7.1
• 5.7.2
• 5.7.3
• 5.7.4
• 5.7.5
• 5.7.6
• 5.7.7
• 5.7.8
• 5.7.9
• 5.7.10
• 5.7.11
• 5.7.12
• 5.7.13
• 5.7.14
• 5.7.15
• 5.7.16
• 6.0.0
• 6.0.1
• 6.0.2
• 6.0.3
• 6.0.4
• 6.0.5

Website

• Product: https://github.com/contao/contao/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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