CVE-2026-55676
HIGHCVE-2026-55676 is a high-severity (CVSS 8.8) Unrestricted File Upload vulnerability. O3 Security confirms whether CVE-2026-55676 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
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…
Description
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.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2026-55676 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-55676 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-55676. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-55676 in your dependencies?
O3 detects CVE-2026-55676 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.