CVE-2026-109390: Critical AnyDesk Linux RCE - What It Is and How to Respond

CVE-2026-109390 is a critical (CVSS 9.8) pre-authentication remote code execution (RCE) flaw in AnyDesk for Linux versions 8.0.0 to 8.0.2. An attacker who can reach the AnyDesk service over the network can run code as root, with no credentials and no click from the user. This guide explains what the AnyDesk Linux RCE is and how to respond: update to AnyDesk for Linux 8.0.3 or later now, because working exploit code is public.

• Affected: AnyDesk for Linux 8.0.0 up to (not including) 8.0.3

• Fixed in: 8.0.3 (released June 2026); 8.1.0 is the current Linux release

• Exploit status: public proof-of-concept ("AnyPwn"); no confirmed in-the-wild exploitation and not in the CISA KEV catalogue as of 19 October 2026

• Windows and macOS: AnyDesk recommends updating to 9.7.8+ (Windows) and 9.7.2+ (macOS) as a precaution

What is CVE-2026-109390?

CVE-2026-109390 is a heap-based buffer overflow in the AnyDesk session protocol, reachable before any authentication. In the stream packet handler for mode 5, a payload length supplied by the attacker is not validated before it is used in a memory allocation. A crafted packet can therefore write attacker data past the allocated buffer and hijack execution (CVE record).

On Linux, the AnyDesk service (anydesk --service) normally runs as root and listens on TCP 7070 for direct connections. Successful exploitation gives full control of the host without the user ever approving a desktop session.

Notably, the fix shipped silently in June 2026, almost four months before the CVE was assigned. Vulnerability scanners that rely on CVE feeds could not flag the issue during that window.

Which AnyDesk versions are affected?

Linux installations from 8.0.0 up to 8.0.2 are vulnerable; Windows and macOS share the underlying flaw but have no known exploitation.

The public PoC targets 8.0.2 specifically, but the official affected range covers all of 8.0.0–8.0.2. Treat every Linux host below 8.0.3 as exposed.

Why this vulnerability matters

The combination of root privileges, no authentication and public exploit code makes this a patch-now issue, not a next-cycle item.

• Root by default. Remote access tools run as privileged services, so one exploit yields full host compromise: credential theft, persistence and lateral movement.

• Large exposed footprint. Qi-AnXin CERT counted roughly 21,500 internet-reachable AnyDesk assets globally linked to this flaw (source).

• Firewalling port 7070 is not a full fix. Qi-AnXin reports the vulnerable code path is also reachable through AnyDesk relay connections, so blocking direct traffic reduces exposure but does not remove it.

• Ransomware precedent. Remote-access software is a favoured initial-access vector; a weaponised PoC typically shortens the time to mass exploitation.

• Compliance impact. For PCI DSS environments, Requirement 6.3.3 expects critical patches within one month; a public PoC justifies a far shorter internal SLA. Remote-access tooling in the cardholder data environment also falls under Requirement 8 controls.

How to fix CVE-2026-109390: step by step

Upgrading to AnyDesk for Linux 8.0.3 or later is the only complete fix; everything else is temporary risk reduction.

1. Inventory every AnyDesk install. Check version and exposure on each Linux host:

   bash

   anydesk --version
   sudo ss -tlnp | grep ':7070'

2. Upgrade from the official source only. Use the AnyDesk repository or anydesk.com/downloads, then restart the service:

   bash

   # Debian / Ubuntu
   sudo apt update && sudo apt install --only-upgrade anydesk
   # RHEL / Fedora / Rocky
   sudo dnf upgrade anydesk
   sudo systemctl restart anydesk
   anydesk --version   # confirm 8.0.3 or later

3. If you cannot patch today, restrict TCP 7070. Allow only trusted management ranges, then deny the rest (ufw evaluates rules in order):

   bash

   sudo ufw allow from 10.20.0.0/24 to any port 7070 proto tcp
   sudo ufw deny 7070/tcp

   
   Replace the subnet with your own admin network. Remember that relay connections may still reach the flaw.

4. Remove what you do not need. Uninstall AnyDesk from servers where it is not business-critical, or stop the service until patched (sudo systemctl disable --now anydesk).

5. Hunt for signs of compromise. Review unexpected anydesk service crashes or restarts (journalctl -u anydesk), unusual child processes spawned by the AnyDesk process, new root-owned cron jobs, SSH keys or systemd units, and the trace log at /var/log/anydesk.trace. Compare findings with the indicators in the official AnyDesk Trust Center advisory.

6. Patch Windows and macOS clients too. Move to 9.7.8+ and 9.7.2+ respectively in the next maintenance window.

7. Close the governance gap. Add remote-access tools to your asset inventory and vendor changelog monitoring, since this fix shipped months before a CVE existed.