# CVE-2026-76866: Netcore NR255-V OS command argument injection in DDNS

Source: https://junglewise.ai/threats/cve-2026-76866-netcore-nr255-v-os-command-argument-injection-in-ddns  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-15. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-76866 · Severity: high · CVSS 7.2 · Published 2026-09-15

The Netcore NR255-V is a wireless router whose firmware includes a DDNS (Dynamic DNS) configuration feature. The feature contains a vulnerability where user-supplied input is not properly sanitized before being used to build system commands executed with root privileges. An authenticated attacker can inject additional command arguments through the DDNS parameters, potentially gaining complete control over the router.

Technologies: [Netcore NR255-V](https://junglewise.ai/threats/technologies/nr255-v). Vendors: [Netcore](https://junglewise.ai/threats/vendors/netcore).

## Quick answers

**Is CVE-2026-76866 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-76866 being exploited in the wild.

**How severe is CVE-2026-76866?** High severity, with a CVSS score of 7.2, published 15 September 2026.

**Which products and versions are affected?** Netcore NR255-V 1.5.130703.

**Is there a fix for CVE-2026-76866?** 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-2026-76866 attacked?** It is attacked over the network, in device firmware.

**Am I affected by CVE-2026-76866?** Check whether you run Netcore NR255-V 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.

## Technical details

This vulnerability is an OS command argument injection (CWE-88) in the DDNS management component of Netcore NR255-V firmware version 1.5.130703. The vulnerable code is located in DDNSset_cgi.c and ddns_Proc.c, where unquoted user-supplied DDNS input is directly concatenated into command lines executed by the system with root privileges. The attack vector requires network access and administrative authentication to the router's web interface. By injecting shell metacharacters and argument delimiters into DDNS parameters, an attacker can break out of the intended command context and execute arbitrary commands with root privileges. No public patch information is currently available.

## Affected products

- Netcore NR255-V 1.5.130703

## Timeline

- 2026-09-04: disclosed
- 2026-09-15: advisory: NVD published CVE-2026-76866

## References

- [https://github.com/draw-ctf/netcore-router-public-refs/blob/main/2026.08.19-netcore-nr255v-ddns-argv-injection.md](https://github.com/draw-ctf/netcore-router-public-refs/blob/main/2026.08.19-netcore-nr255v-ddns-argv-injection.md)
- [https://www.vulncheck.com/advisories/netcore-nr255-v-1.5.130703-os-command-argument-injection-via-unquoted-ddns-parameters](https://www.vulncheck.com/advisories/netcore-nr255-v-1.5.130703-os-command-argument-injection-via-unquoted-ddns-parameters)

## Related threats

- [Netcore NR255-V stored cross-site scripting in L7 content management](https://junglewise.ai/threats/cve-2026-92257-netcore-nr255-v-stored-cross-site-scripting-in-l7-content)
- [Netcore NR255-V sensitive information disclosure in VPN configuration handlers](https://junglewise.ai/threats/cve-2026-92256-netcore-nr255-v-sensitive-information-disclosure-in-vpn)
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- [Netcore NR255-V stored cross-site scripting in DHCP and ARP hostname fields](https://junglewise.ai/threats/cve-2026-76873-netcore-nr255-v-stored-cross-site-scripting-in-dhcp-and-arp)
- [Netcore NR255-V stored cross-site scripting in DHCP and ACL management](https://junglewise.ai/threats/cve-2026-76872-netcore-nr255-v-stored-cross-site-scripting-in-dhcp-and-acl)