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Hi,

Please find attached a security advisory that describes some
vulnerabilities we discovered in the Zyxel uOS Linux-based operating
system.

* Title: Local privilege escalation via Zyxel fermion-wrapper
* Product: USG FLEX H Series
* OS: Zyxel uOS V1.31 (and potentially earlier versions)
* Author: Marco Ivaldi <marco.ivaldi () hnsecurity it>
* Date: 2025-04-23
* CVE ID: CVE-2025-1731 (see discussion in "5 - Remediation" below)
* Severity: High - 7.8 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
* CWE ID: CWE-61 - https://cwe.mitre.org/data/definitions/61.html
* HN Security URLs:
  * https://github.com/hnsecurity/vulns/blob/main/HNS-2025-10-zyxel-fermion.txt
  * https://github.com/0xdea/exploits/blob/master/zyxel/raptor_fermion
  * https://security.humanativaspa.it/local-privilege-escalation-on-zyxel-usg-flex-h-series-cve-2025-1731
* Vendor URLs:
  * 
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-incorrect-permission-assignment-and-improper-privilege-management-vulnerabilities-in-usg-flex-h-series-firewalls-04-22-2025
  * https://community.zyxel.com/en/discussion/28988/usg-flex-h-series-v1-32patch-0-firmware-release

For additional information, please refer to our vulnerability writeup:
https://security.humanativaspa.it/local-privilege-escalation-on-zyxel-usg-flex-h-series-cve-2025-1731/

Regards,

-- 
Marco Ivaldi
https://0xdeadbeef.info/
"When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl."

Attachment: HNS-2025-10-zyxel-fermion.txt
Description:

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• HNS-2025-10 - HN Security Advisory - Local privilege escalation in Zyxel uOS Marco Ivaldi (Apr 23)