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CVE-2026-53593— FreeScout Vulnerable to Authenticated Remote Code Execution via incomplete upload extension denylist (.pht) — bypass of CVE-2025-48471

Quick assessment

Affected
freescout-help-desk freescout
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

FreeScout是FreeScout公司开源的一个使用 PHP(Laravel 框架)构建的超轻量级且功能强大的免费开源帮助台和共享收件箱。 FreeScout 1.8.224之前版本存在任意文件上传漏洞，该漏洞源于denylist不完整，未覆盖.pht扩展名，可能导致经过身份验证的代理上传.pht Web脚本并执行任意命令。

CVSS 8.8 · High EPSS 0.35% · P29

Affected Version Matrix 1

VendorProduct Version RangeStatus
freescout-help-desk freescout < 1.8.224 affected
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I. Basic Information for CVE-2026-53593

Vulnerability Information
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Vulnerability Title
FreeScout Vulnerable to Authenticated Remote Code Execution via incomplete upload extension denylist (.pht) — bypass of CVE-2025-48471
Source: CVE Program / CVE List V5
Vulnerability Description
FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. Prior to version 1.8.224, the denylist that neutralizes dangerous file uploads (`Helper::$restricted_extensions`) is incomplete: it does not cover the `.pht` extension. The authenticated upload endpoint `POST /uploads/upload` (`SecureController@upload`) stores files with their original extension into the web-accessible directory `storage/app/public/uploads/` (served at `/storage/uploads/`). On the standard Apache + `libapache2-mod-php` deployment, the default handler `<FilesMatch ".+\.ph(ar|p[3457]?|t|tml)$">` executes `.pht`, so **any authenticated agent can upload a `.pht` web shell and run arbitrary commands as the web-server user** (`www-data`). This is a direct bypass of the fix for CVE-2025-48471, which added `phtml`/`phar` but not `pht` (nor `phtm`, `phps`). Version 1.8.224 contains an updated fix.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
危险类型文件的不加限制上传
Source: CVE Program / CVE List V5
Vulnerability Title
FreeScout 任意文件上传漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
FreeScout是FreeScout公司开源的一个使用 PHP(Laravel 框架)构建的超轻量级且功能强大的免费开源帮助台和共享收件箱。 FreeScout 1.8.224之前版本存在任意文件上传漏洞，该漏洞源于denylist不完整，未覆盖.pht扩展名，可能导致经过身份验证的代理上传.pht Web脚本并执行任意命令。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
freescout-help-desk freescout < 1.8.224 -

II. Public POCs for CVE-2026-53593

# POC Description Source Link Shenlong Link
AI-Generated POC Verified env Premium
Qwen3.6-35B-A3B · 8508 chars
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III. Intelligence Information for CVE-2026-53593

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Vendor Advisories for CVE-2026-53593 (1)

Same Patch Batch · freescout-help-desk · 2026-07-20 · 8 CVEs total

CVE-2026-53595 9.4 CRITICAL FreeScout vulnerable to anonymous account takeover via /user-setup empty invite_hash on My
CVE-2026-53591 8.6 HIGH FreeScout Vulnerable to Unauthenticated Conversation Thread Injection via HMAC Length Bypa
CVE-2026-48812 7.5 HIGH FreeScout Allows Unauthenticated Access to Legacy Attachment Files
CVE-2026-45295 6.5 MEDIUM FreeScout Vulnerable to Unauthenticated Thread Read-Status Manipulation and Conversation E
CVE-2026-53596 5.3 MEDIUM FreeScout has unrestricted file upload without rate limiting that leads to resource exhaus
CVE-2026-53594 4.9 MEDIUM FreeScout has Arbitrary File Read in App Logs Viewer via Forged Encrypted Path
CVE-2026-53592 4.6 MEDIUM FreeScout vulnerable to prototype pollution in getQueryParam

IV. Related Vulnerabilities

Same product: freescout
Same vendor: freescout-help-desk
Same weakness: CWE-434