CVE-2026-6643
A stack-based buffer overflow vulnerability in the VPN Clients on the ADM
Description
A stack-based buffer overflow vulnerability was found in the VPN Clients on the ADM. The issue stems from the use of unbounded sscanf() and passing user-controlled data directly to printf(). Due to the lack of PIE and Stack Canary protections, an authenticated remote attacker can exploit these to execute arbitrary code as the web server user. Affected products and versions include: from ADM 4.1.0 through ADM 4.3.3.RR42 as well as from ADM 5.0.0 through ADM 5.1.2.REO1.
INFO
Published Date :
April 20, 2026, 7:16 a.m.
Last Modified :
April 22, 2026, 2:43 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | [email protected] | ||||
| CVSS 4.0 | HIGH | f35eaae9-79f2-4d0d-a5c7-7bea6ed6be77 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update VPN clients to version ADM 4.3.3.RR42 or ADM 5.1.2.REO1.
- Enable PIE and Stack Canary protections.
- Avoid passing user data directly to printf().
- Use bounded sscanf() function calls.
Public PoC/Exploit Available at Github
CVE-2026-6643 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-6643.
| URL | Resource |
|---|---|
| https://www.asustor.com/security/security_advisory_detail?id=54 | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-6643 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-6643
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
ASUSTOR ADM 5.1.2 vpnupload.cgi Format String & Stack Buffer Overflow RCE (CVE-2026-6643)
exploit cve-2026-6643
Python
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-6643 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-6643 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Apr. 22, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H Added CPE Configuration OR *cpe:2.3:o:asustor:data_master:*:*:*:*:*:*:*:* versions from (including) 5.0.0.ra82 up to (excluding) 5.1.2.reo1 *cpe:2.3:o:asustor:data_master:*:*:*:*:*:*:*:* versions from (including) 4.1.0.rhu2 up to (excluding) 4.3.3.RR42 Added Reference Type ASUSTOR, Inc.: https://www.asustor.com/security/security_advisory_detail?id=54 Types: Vendor Advisory -
New CVE Received by [email protected]
Apr. 20, 2026
Action Type Old Value New Value Added Description A stack-based buffer overflow vulnerability was found in the VPN Clients on the ADM. The issue stems from the use of unbounded sscanf() and passing user-controlled data directly to printf(). Due to the lack of PIE and Stack Canary protections, an authenticated remote attacker can exploit these to execute arbitrary code as the web server user. Affected products and versions include: from ADM 4.1.0 through ADM 4.3.3.RR42 as well as from ADM 5.0.0 through ADM 5.1.2.REO1. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-121 Added Reference https://www.asustor.com/security/security_advisory_detail?id=54