CVE-2026-40497

Published Apr 21, 2026

Last updated 8 days ago

CVSS high 8.1

Overview

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.
Source
security-advisories@github.com
NVD status
Analyzed
Products
freescout

Risk scores

CVSS 3.1

Type
Secondary
Base score
8.1
Impact score
5.8
Exploitability score
1.7
Vector string
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N
Severity
HIGH

Weaknesses

security-advisories@github.com
CWE-79

Social media

Hype score
Not currently trending

Configurations

Related CVEs

  1. FreeScout is a free self-hosted help desk and shared mailbox. Prior to version 1.8.213, FreeScout's linkify() function in app/Misc/Helper.php converts plain-text URLs in email bodies into HTML anchor tags without escaping double-quote characters (") in the URL. HTMLPurifier (called first via getCleanBody()) preserves literal " characters in text nodes. linkify() then wraps URLs including those " chars inside an unescaped href="..." attribute, breaking out of the href and injecting arbitrary HTML attributes. Version 1.8.213 fixes the issue.•CVE-2026-40565
  2. FreeScout is a free self-hosted help desk and shared mailbox. Prior to version 1.8.213, an unauthenticated attacker can access diagnostic and system tools that should be restricted to administrators. The /system/cron endpoint relies on a static MD5 hash derived from the APP_KEY, which is exposed in the response and logs. Accessing these endpoints reveals sensitive server information (Full Path Disclosure), process IDs, and allows for Resource Exhaustion (DoS) by triggering heavy background tasks repeatedly without any rate limiting. The cron hash is generated using md5(APP_KEY . 'web_cron_hash'). Since this hash is often transmitted via GET requests, it is susceptible to exposure in server logs, browser history, and proxy logs. Furthermore, the lack of rate limiting on these endpoints allows for automated resource exhaustion (DoS) and brute-force attempts. Version 1.8.213 fixes the issue.•CVE-2026-40498
  3. FreeScout is a free self-hosted help desk and shared mailbox. Prior to version 1.8.213, attachment download tokens are generated using a weak and predictable formula: `md5(APP_KEY + attachment_id + size)`. Since attachment_id is sequential and size can be brute-forced in a small range, an unauthenticated attacker can forge valid tokens and download any private attachment without credentials. Version 1.8.213 fixes the issue.•CVE-2026-40496
  4. FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. Prior to 1.8.212, FreeScout does not take the limit_user_customer_visibility parameter into account when merging customers. This vulnerability is fixed in 1.8.212.•CVE-2026-39384
  5. FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. Prior to 1.8.212, the endpoint GET /thread/read/{conversation_id}/{thread_id} does not require authentication and does not validate whether the given thread_id belongs to the given conversation_id. This allows any unauthenticated attacker to mark any thread as read by passing arbitrary IDs, enumerate valid thread IDs via HTTP response codes (200 vs 404), and manipulate opened_at timestamps across conversations (IDOR). This vulnerability is fixed in 1.8.212.•CVE-2026-35584

References

Sources include official advisories and independent security research.