Quick.Cart theme upload flaw leads to RCE — time to treat your ecommerce supplier as a security risk

Quick.Cart theme upload flaw hands attackers a web shell on a plate — why your ecommerce supplier should be on your risk register

There’s nothing like a critical remote code execution hole in an online shop to make the boardroom pay attention. Less than an hour ago a vulnerability was disclosed in Quick.Cart’s theme selection mechanism (CVE-2025-67684) that combines Local File Inclusion and path traversal with weak upload validation. In short: a privileged user can upload arbitrary file contents while only the filename extension is checked, and an attacker can include and execute uploaded PHP code, resulting in Remote Code Execution on the server. Only version 6.7 was tested and confirmed as vulnerable; the vendor was notified early but has not provided a detailed response. Severity is listed as 9.4 (CRITICAL).

What happened — the facts, plainly

Quick.Cart, an e-commerce platform, has a flaw in its theme selection/upload handling which allows a privileged upload to turn into server‑side code execution. The vulnerability was published approximately 38 minutes ago and is rated critical. The vendor was told early but hasn’t clarified which other versions, if any, are affected.

Why this keeps business leaders awake

For any organisation running Quick.Cart (or any third‑party ecommerce stack), a vulnerability like this is not just a developer’s problem — it’s a commercial one. Remote code execution can lead to data theft, card‑skimming, defacement, persistent backdoors, lateral movement into other systems, ransomware, regulatory exposure and cancelled contracts. Customers lose trust faster than you can say “chargeback”. Regulators look unkindly at organisations that haven’t managed third‑party risk; insurers will want to know why privileged upload paths weren’t restricted and whether patching timelines were reasonable.

Who is affected?

Customers and cardholders whose data flows through the platform, staff who rely on the site for orders, suppliers integrated with the system, and the organisation’s reputation and contractual partners. Any environment that exposes theme upload or administration functions is at risk if the platform or its deployment hasn’t been hardened.

How this kind of weakness is commonly abused (and how nasty it gets)

If an attacker can upload and execute PHP, they can run arbitrary commands, drop web shells, harvest credentials, pivot to back‑end databases and quietly harvest personal data for weeks or months. They can also install skimmers for payment data or deploy ransomware to encrypt backups. Operational downtime can be extensive, recovery costly and forensic investigations expensive and reputationally painful.

Treat untested backups like a parachute you’ve never bothered to open — it feels reassuring until you jump.

What sensible organisations should do right now

• Inventory and isolate: identify any Quick.Cart instances and confirm which versions are running (note: only 6.7 was tested as vulnerable, but don’t assume other versions are safe).

• Restrict privileged uploads: limit who can upload themes or files and put those functions behind additional controls (segregated admin networks, VPNs, MFA, just‑in‑time admin access).

• Harden file handling: never trust filename extensions alone — implement server‑side content inspection, deny execution in upload directories (disable PHP execution), and serve media from a separate domain or storage bucket when possible.

• WAF and detection: deploy or tune web application firewalls and intrusion detection to block LFI/path traversal patterns and to alert on suspicious file executions.

• Patch and vendor engagement: push for vendor guidance and patches; if they don’t respond, consider mitigating at the deployment level and raise supplier risk through your procurement and supplier‑management processes.

• Incident readiness: ensure incident response playbooks are current, forensic logging is enabled, backups are isolated and restore‑tested, and escalation paths to legal, privacy and the board are clear.

How ISO standards and Synergos’ services help

An ISO 27001 information security management system would make the supplier and vulnerability management aspects of this much harder to ignore: defined responsibilities, documented supplier risk assessments, change control and regular vulnerability scanning are all part of a mature ISMS. ISO 27001’s requirement to treat third‑party risks would force a conversation about vendor responsiveness and patch SLAs long before an exploit appears.

ISO 22301 business continuity planning helps you keep selling and paying staff while you remediate — crucial for retail and any operation with time‑sensitive revenue. If theme uploads are a single point of failure, your BCMS should have alternatives mapped out.

Practical baseline controls like Cyber Essentials and IASME reduce trivial attack surfaces; security awareness training via usecure helps developers and admins spot risky configuration and social engineering that an attacker might use to gain privileged upload access. If supplier quality is a concern, tie this into ISO 9001‑style supplier assurance and consider Synergos’ ongoing support packages to help manage remediation and evidence for auditors or insurers.

Practical short checklist — things to do before lunch

1. Confirm where Quick.Cart is used and who has admin/upload privileges.

2. Disable theme uploads or restrict them to a trusted admin group and network segment until mitigations are in place.

3. Block execution in upload directories (web server configuration) and serve uploaded files from a separate origin if possible.

4. Enable MFA for all administrator accounts and review privileged user lists.

5. Turn on verbose logging and forward relevant logs to a central SIEM; set alerts for file upload and PHP execution anomalies.

6. Verify backups are offline or immutable and perform a restore test to ensure recoverability.

If you want to take a structured approach, an ISO 27001 gap assessment will identify the process and control shortfalls, while ISO 22301 work will formalise your continuity responses so that a single exploited upload doesn’t become a multi‑day outage.

One more gentle but firm reminder: relying on filename extension checks is like locking your front door with a ribbon. It looks like a control until someone with intent walks straight through.

Act now: inventory the platform, limit uploads, harden file handling, communicate with your supplier and test your response — because when ecommerce breaks, so do orders, trust and cashflow.