CVE-2026-107844: Contao Path Traversal Vulnerability
MODERATECVE-2026-107844 is a MODERATE (CVSS 5.3) path traversal vulnerability (CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')) affecting Contao libraries in the Packagist ecosystem. The issue involves path traversal in the images controller. Remediation is available by upgrading affected packages to version 5.3.50, 5.7.12.
CVE-2026-107844 at a Glance
Security Impact
CVSS: 5.3
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N).
How to Fix CVE-2026-107844
To remediate this vulnerability, upgrade all affected Contao dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade contao/core-bundle to 5.3.50Upgrade contao/core-bundle to 5.7.12Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for contao/core-bundleHow to Check if You Are Affected
To determine whether your application is affected by CVE-2026-107844, inspect your project dependencies for Contao:
inspect dependencies for contao/core-bundleAnalyze the terminal output to locate any version of Contao in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.3.50), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'), where 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. In Contao, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-107844 Affected Contao Versions
2 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
contao/core-bundle
|
Packagist |
≥ 4.1.0
< 5.3.50
|
5.3.50
|
|
contao/core-bundle
|
Packagist |
≥ 5.4.0-RC1
< 5.7.12
|
5.7.12
|
References
Frequently Asked Questions
What is CVE-2026-107844?
Which Contao versions are affected?
What version fixes CVE-2026-107844?
Is contao/core-bundle affected?
What is the CVSS score of CVE-2026-107844?
What CWE is associated with CVE-2026-107844?
How can I check Packagist dependencies for CVE-2026-107844?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-mrvp-7wmx-5m4h",
"modified" : "2026-10-09T20:53:55Z",
"published" : "2026-10-09T20:53:55Z",
"aliases" : [ "CVE-2026-107844" ],
"summary" : "Contao: Path traversal in the images controller",
"details" : "`ImagesController` joins the user controlled `{path}` onto the configured image target directory with `Path::join()`, which canonicalises `..` segments, and never calls `Path::isBasePath()` to confirm the result stayed inside that directory. An unauthenticated GET with percent encoded dot segments therefore escapes the directory and the file is returned by `BinaryFileResponse`. Reads are bounded to the extensions in `contao.image.valid_extensions`, and paths below the upload directory fail for an unrelated reason, so this is reported as a missing boundary check rather than as a general arbitrary file read. Both Apache with the shipped `public/.htaccess` and nginx with the documented configuration are affected.\n\n### Impact\n\nAny unauthenticated visitor can read files that are deliberately kept outside the document root, anywhere under the project directory, as long as the name ends in one of `contao.image.valid_extensions` (`jpg`, `jpeg`, `gif`, `png`, `tif`, `tiff`, `bmp`, `svg`, `svgz`, `webp`). The route also acts as an existence oracle for arbitrary paths, and on a debug enabled instance the 404 message discloses the absolute filesystem path.\n\n**Honesty caveat, stated because it lowers the severity.** The reporter could not use this to read protected member folders: every path below the upload directory returns 500 for the reason given under Details, so the practically reachable set is image typed files outside `files/`.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Packagist",
"name" : "contao/core-bundle"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "4.1.0"
}, {
"fixed" : "5.3.50"
} ]
} ]
}, {
"package" : {
"ecosystem" : "Packagist",
"name" : "contao/core-bundle"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "5.4.0-RC1"
}, {
"fixed" : "5.7.12"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/contao/contao/security/advisories/GHSA-mrvp-7wmx-5m4h"
}, {
"type" : "WEB",
"url" : "https://github.com/contao/contao/commit/867c055122fdf12220f973f862082037b695b9bd"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/contao/contao"
}, {
"type" : "WEB",
"url" : "https://github.com/contao/contao/releases/tag/5.3.50"
}, {
"type" : "WEB",
"url" : "https://github.com/contao/contao/releases/tag/5.7.12"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-22" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2026-10-09T20:53:55Z",
"nvd_published_at" : null
}
}