PatchTheCVECVE-2026-6643: A stack-based buffer overflow vulnerability was found in the VPN Clients on the ADM
CVE-2026-6643 is a critical-severity flaw (CVSS 9.9) affecting data master. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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
Why this priority
- Critical severity
A fixed release or distro patch exists.
Risk facts
| CVSS score | 9.9 (Critical) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | Low |
| User interaction | None |
| EPSS exploit chance | 0.5% (top 60%) |
| CISA exploited list | No |
| Weakness | CWE-121 |
| Published | 2026-04-20 |
| Last modified | 2026-10-26 |
Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-6643?
data master: upgrade to 4.3.3.RR42, 5.1.2.reo1. Exact commands for each OS are on this page.
Is CVE-2026-6643 being exploited?
CVE-2026-6643 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-6643 affect?
CVE-2026-6643 affects data master. Severity is critical (CVSS 9.9). 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 protectio
How urgent is CVE-2026-6643?
Priority 45/100. Critical severity
Related CVEs
- CVE-2026-6644 CRITICAL 9.1 UPGRADE A command injection vulnerability was found in the PPTP VPN Clients on the ADM
- CVE-2026-67248 HIGH 8.8 UPGRADE A stack-based buffer overflow vulnerability was found in the File Explorer on the ADM
- CVE-2026-18186 HIGH 8.1 UPGRADE A stored format string vulnerability was found in the FTP Backup on the ADM
- CVE-2026-18187 HIGH 8.1 UPGRADE A format string vulnerability was found in the Internal Backup on the ADM
- CVE-2026-18188 HIGH 8.1 UPGRADE A format string vulnerability was found in the Rsync Backup on the ADM