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Findings

CVE-2026-107844

Contao: Path traversal in the images controller

Published Oct 9, 2026 · updated Oct 9, 2026

joins the user controlled onto the configured image target directory with , which canonicalises segments, and never calls 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 . Reads are bounded to the extensions in , 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 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 ( , , , , , , , , , ). 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 .

Timeline

Detection, updates, and resolution for this record.

  1. Oct 9, 2026 · Catalog

    Detected

    joins the user controlled onto the configured image target directory with , which canonicalises segments, and never calls 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 . Reads are bounded to the extensions in , and paths below the upload directory fail for an unrelated reason,

  2. Oct 9, 2026 · Catalog

    Fix available

    Packagist contao/core-bundle 4.1.0 → 5.3.50

  3. Oct 9, 2026 · Catalog

    Fix available

    Packagist contao/core-bundle 5.4.0-RC1 → 5.7.12

  4. Oct 9, 2026 · Catalog

    Updated

    joins the user controlled onto the configured image target directory with , which canonicalises segments, and never calls 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 . Reads are bounded to the extensions in , and paths below the upload directory fail for an unrelated reason,

Affected

  • Packagist contao/core-bundle4.1.0 → 5.3.50
  • Packagist contao/core-bundle5.4.0-RC1 → 5.7.12

Sources

References