# CVE-2026-109161: Welotec TK router buffer overflow in Digital I/O function

Source: https://junglewise.ai/threats/cve-2026-109161-insufficient-bounds-checking-in-the-digital-i-o-function-may  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-03. Updated: 2026-11-03  
License: CC BY 4.0 with a link back

CVE-2026-109161 · Severity: medium · CVSS 4.9 · Published 2026-11-03

Welotec TK routers are industrial network appliances used to provide VPN and remote connectivity for critical infrastructure. A buffer overflow vulnerability in the Digital I/O management function allows a remote attacker with administrative privileges to trigger a denial of service condition, disrupting network connectivity and operations.

Technologies: [Welotec TK100](https://junglewise.ai/threats/technologies/tk100), [Welotec TK500-v2](https://junglewise.ai/threats/technologies/tk500-v2), [Welotec TK500-v3](https://junglewise.ai/threats/technologies/tk500-v3). Vendors: [Welotec](https://junglewise.ai/threats/vendors/welotec).

## Quick answers

**Is CVE-2026-109161 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-109161 being exploited in the wild.

**How severe is CVE-2026-109161?** Medium severity, with a CVSS score of 4.9, published 3 November 2026.

**Which products and versions are affected?** Welotec TK100 before 3.5.116; Welotec TK500-v2 before 1.0.124; Welotec TK500-v3 before 1.0.123.

**Is there a fix for CVE-2026-109161?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-109161 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-109161?** Check whether you run Welotec TK100, Welotec TK500-v2 or Welotec TK500-v3 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.

## Affected products

- Welotec TK100 before 3.5.116
- Welotec TK500-v2 before 1.0.124
- Welotec TK500-v3 before 1.0.123

## Timeline

- 2026-11-03: disclosed

## References

- [https://www.certvde.com/en/advisories/VDE-2026-119/](https://www.certvde.com/en/advisories/VDE-2026-119/)

## Related threats

- [Welotec TK routers command injection in IPsec VPN](https://junglewise.ai/threats/cve-2026-105982-improper-input-validation-in-the-ipsec-vpn-function-may-allow-a)
- [Welotec TK routers OS command injection in Digital I/O](https://junglewise.ai/threats/cve-2026-105981-improper-input-validation-in-the-digital-i-o-function-may-allow)
- [Welotec TK router ZeroTier VPN command injection](https://junglewise.ai/threats/cve-2026-105979-improper-input-validation-in-the-zerotier-vpn-function-may-allow)
- [Welotec TK router OS command injection in management functions](https://junglewise.ai/threats/cve-2026-105978-improper-input-validation-in-management-control-functions-may)