CVE-2025-54366 FreeScout's deserialization of untrusted data leads to Remote Code Execution
Authenticated attackers with APP_KEY can achieve remote code execution via unsafe deserialization in FreeScout help desk.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-54366?
CVE-2025-54366 is a high-severity unsafe deserialization vulnerability in freescout-help-desk freescout, published on 26 Jul 2025. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
FreeScout is a lightweight free open source help desk and shared inbox built with PHP (Laravel framework). In versions 1.8.185 and below, there is a critical deserialization vulnerability in the /conversation/ajax endpoint that allows authenticated users with knowledge of the APP_KEY to achieve remote code execution. The vulnerability occurs when the application processes the attachments_all and attachments POST parameters through the insecure Helper::decrypt() function, which performs unsafe deserialization of user-controlled data without proper validation. This flaw enables attackers to create arbitrary objects and manipulate their properties, leading to complete compromise of the web application. This is fixed in version 1.8.186.
Weakness: CWE-502
Which versions are affected by CVE-2025-54366?
It affects 1 product.
Products include Freescout Freescout.
How do I fix CVE-2025-54366?
No fix has been published for CVE-2025-54366 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2025-54366 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-54366 exists.
Other vulnerabilities in freescout-help-desk freescout
- CVE-2026-28289 FreeScout 1.8.206 Patch Bypass for CVE-2026-27636 via Zero-Width Space Character Leads to Remote Code Execution
- CVE-2026-27637 FreeScout's Predictable Authentication Token Enables Account Takeover
- CVE-2026-32754 FreeScout: Stored XSS via Unescaped Email Template Rendering ({!! $thread->body !!})
- CVE-2024-29185 FreeScout OS Command Injection vulnerability
- CVE-2026-40498 FreeScout has Authentication Bypass and Information Disclosure in SystemController via /system/cron
Sources
Also known as GHSA-vcc2-6r66-gvvj.