Buffer overflow in Asustor Data Master
CVE-2026-6643
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.9 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.008 (53.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 53.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.008 · change: +0.003
Affected products
- Asustor Data Master
- Asustor Inc. Adm — versions 4.1.0, 5.0.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- www.asustor.com/security/security_advisory_detail (vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-6643?
- CVE-2026-6643 is a critical-severity vulnerability in Asustor Data Master, classified under Stack-based Buffer Overflow. CVSS score: 9.9/10. Published 2026-04-20.
- How severe is CVE-2026-6643?
- Critical severity. CVSS v3 base score is 9.9 out of 10.
- Is CVE-2026-6643 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.