Summary
Contao: Path traversal in the images controller
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.
Impact
Any 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.
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/.
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
CVE-2026-107844 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.3.50, 5.7.12); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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contao/core-bundle to 5.3.50 or later; contao/core-bundle to 5.7.12 or later
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Frequently Asked Questions
- What is CVE-2026-107844? CVE-2026-107844 is a medium-severity path traversal vulnerability in contao/core-bundle (composer), affecting versions >= 4.1.0, < 5.3.50. It is fixed in 5.3.50, 5.7.12. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
- How severe is CVE-2026-107844? CVE-2026-107844 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of contao/core-bundle are affected by CVE-2026-107844? contao/core-bundle (composer) versions >= 4.1.0, < 5.3.50 is affected.
- Is there a fix for CVE-2026-107844? Yes. CVE-2026-107844 is fixed in 5.3.50, 5.7.12. Upgrade to this version or later.
- Is CVE-2026-107844 exploitable, and should I be worried? Whether CVE-2026-107844 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-107844 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-107844?
- Upgrade
contao/core-bundleto 5.3.50 or later - Upgrade
contao/core-bundleto 5.7.12 or later
- Upgrade