Stack-based Buffer Overflow in Asustor VPN Clients
CVE-2026-6643

8.6HIGH

Key Information:

Vendor

Asustor Inc.

Status
Adm
Vendor
CVE Published:
20 April 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-6643?

A stack-based buffer overflow vulnerability exists in the VPN Clients on Asustor's ADM platform. This flaw results from the unbounded use of the sscanf() function and the direct incorporation of user-controlled data into printf() calls. The absence of protection mechanisms such as Position Independent Executables (PIE) and Stack Canaries allows authenticated remote attackers to exploit this vulnerability, enabling them to execute arbitrary code under the privileges of the web server user. Organizations utilizing affected versions of Asustor's VPN Clients should consider taking immediate steps to mitigate the risks linked with this vulnerability.

Affected Version(s)

ADM Linux 4.1.0 <= 4.3.3.RR42

ADM Linux 5.0.0 <= 5.1.2.REO1

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-6643
Created by mlgzackfly

References

https://www.asustor.com/security/security_advisory_detail...
vendor-advisory

CVSS V4

Score:
8.6
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

YU-XIANG HUANG (mlgzackfly)
.