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DRUPAL-CORE-2026-009
Quick fix
DRUPAL-CORE-2026-009 — drupal/core: upgrade to the fixed version with the command below.
composer require drupal/core:^10.5.12Details
The JSON:API and REST modules allow you to upload image files to image fields.
The validation rules check the file extension of the uploaded file but not the file MIME type. This may allow a malicious user to upload a file that is not an image.
Certain web-server configurations may serve the uploaded file with its actual MIME type rather than an image type. This may lead to cross-site scripting (XSS) or other unexpected behavior.
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