CVE-2026-55676
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk22th percentile - higher than 22% of all known CVEs
Summary
Malcolm, a network traffic analysis tool, has a vulnerability in its file-upload component (FilePond PHP backend). The allowed file types list is empty by default, so all extensions are accepted, and filenames keep the .php extension. An authenticated user with the ROLE_UPLOAD role can upload a PHP file and execute it as www-data.
Risk Assessment
An attacker with upload-only permissions can execute arbitrary PHP code in the container, potentially leading to full system compromise or privilege escalation.
Recommendation
Update Malcolm to version 26.06.1 or later, which fixes this vulnerability. Additionally, configure the allowed file types list and restrict access to the upload endpoint.
Original NVD description (English source)
Malcolm is a network traffic analysis tool suite. The file-upload component (FilePond PHP backend) accepts uploads at `POST /server/php/submit.php` and stores them in a directory served by the same nginx and php-fpm instance. The allow-list that should restrict accepted file types is an empty array by default (`file-upload/php/config.php:16`), so the type check is a no-op and every extension is accepted. The filename sanitizer keeps the `.php` extension intact. Committed files land in `/var/www/upload/server/php/files` (`file-upload/php/config.php:7`), and the component's nginx routes any URL ending in `.php` to php-fpm. An authenticated `GET /server/php/files/<name>.php` then executes the uploaded code as `www-data`. Prior to version 26.06.1, in RBAC mode, the upload endpoint is reachable by the granular `ROLE_UPLOAD` role (`nginx/lua/nginx_auth_helpers.lua:71`), a role intended only for submitting capture files. As a result, a user holding the upload-only role runs arbitrary PHP as `www-data` inside the file-upload container. Version 26.06.1 fixes the issue.