# CVE-2026-109390: AnyDesk heap buffer overflow in session protocol mode 5

Source: https://junglewise.ai/threats/cve-2026-109390-anydesk-before-8-0-3-allows-unauthenticated-remote-attackers-to  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-12. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-109390 · Severity: critical · CVSS 9.8 · Published 2026-10-12

AnyDesk is a remote desktop application that allows users to control computers remotely. An unauthenticated attacker can exploit a heap buffer overflow in the session protocol to execute arbitrary commands as the root user on Linux systems before the user approves any desktop control request. This vulnerability allows complete system compromise through remote code execution.

Technologies: [AnyDesk](https://junglewise.ai/threats/technologies/anydesk). Vendors: [AnyDesk](https://junglewise.ai/threats/vendors/anydesk).

## Quick answers

**Is CVE-2026-109390 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-109390 being exploited in the wild.

**How severe is CVE-2026-109390?** Critical severity, with a CVSS score of 9.8, published 12 October 2026.

**Which products and versions are affected?** AnyDesk before 8.0.3.

**Is there a fix for CVE-2026-109390?** Yes: fixed in 8.0.3. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-109390 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-109390?** Check whether you run AnyDesk at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 8.0.3

## Technical details

The vulnerability exists in AnyDesk's stream packet handler for mode 5 of the session protocol, where a payload length value is not properly validated before being used in a 32-bit allocation calculation. An attacker can declare a payload length of 0xfffffff0, which when incremented by 0x10 wraps to 0 in 32-bit arithmetic, resulting in a minimal allocation while the object retains the original declared length. This allows heap buffer overflow by copying attacker-controlled bytes beyond the allocation boundaries. The exploit leverages heap grooming and ROP gadgets to achieve unauthenticated remote code execution as root on vulnerable Linux systems.

## Affected products

- AnyDesk AnyDesk before 8.0.3

## Timeline

- 2026-10-12: disclosed
- 2026-10-12: patched: Fixed in version 8.0.3

## References

- [https://anydesk.com/en/changelog/linux](https://anydesk.com/en/changelog/linux)
- [https://github.com/v12-security/pocs/tree/main/anydesk](https://github.com/v12-security/pocs/tree/main/anydesk)

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