Description

FreeScout is a free self-hosted help desk and shared mailbox. Prior to version 1.8.213, FreeScout's `Helper::stripDangerousTags()` removes `<script>`, `<form>`, `<iframe>`, `<object>` but does NOT strip `<style>` tags. The mailbox signature field is saved via POST /mailbox/settings/{id} and later rendered unescaped via `{!! $conversation->getSignatureProcessed([], true) !!}` in conversation views. CSP allows `style-src * 'self' 'unsafe-inline'`, so injected inline styles execute freely. An attacker with access to mailbox settings (admin or agent with mailbox permission) can inject CSS attribute selectors to exfiltrate the CSRF token of any agent/admin who views a conversation in that mailbox. With the CSRF token, the attacker can perform any state-changing action as the victim (create admin accounts, change email/password, etc.) — privilege escalation from agent to admin. This is the result of an incomplete fix of GHSA-jqjf-f566-485j. That advisory reported XSS via mailbox signature. The fix applied `Helper::stripDangerousTags()` to the signature before saving. However, `stripDangerousTags()` only removes `script`, `form`, `iframe`, and `object` tags — it does NOT strip `<style>` tags, leaving CSS injection possible. Version 1.8.213 contains an updated fix.

Weaknesses 1

Affected Products 1

References 3

• github.com https://github.com/freescout-help-desk/freescout/commit/5aa8d633216f65995e80a7d4a921b784acc94df4
  Patch
• github.com https://github.com/freescout-help-desk/freescout/releases/tag/1.8.213
  Release Notes
• github.com https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-fh99-wr77-pxq3
  Vendor Advisory

Remediation

• github.com https://github.com/freescout-help-desk/freescout/commit/5aa8d633216f65995e80a7d4a921b784acc94df4
  Patch