# CVE-2026-76858: Netcore NR255-V stored cross-site scripting in ddns_wan_list_show.cgi

Source: https://junglewise.ai/threats/cve-2026-76858-netcore-nr255-v-stored-cross-site-scripting-in-ddns-wan-list-show  
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-2026-76858 · Severity: medium · CVSS 4.8 · Published 2026-09-15

The Netcore NR255-V is a wireless router used in home and small business networks. A vulnerability in its web-based DDNS (Dynamic DNS) configuration interface allows attackers who can access the router's admin panel to inject malicious code that persists and executes whenever any administrator views the affected DDNS configuration page, potentially compromising the router's settings or the administrator's session.

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

## Quick answers

**Is CVE-2026-76858 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-76858 being exploited in the wild.

**How severe is CVE-2026-76858?** Medium severity, with a CVSS score of 4.8, published 15 September 2026.

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

**Is there a fix for CVE-2026-76858?** 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-2026-76858 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-76858?** 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

The vulnerability is a stored cross-site scripting (XSS) flaw in the ddns_wan_list_show.cgi web interface component, caused by unsafe eval() handling of DDNS configuration data. An attacker with administrative access to the router can inject malicious JavaScript through the DDNS configuration path, which is stored and reflected when the page is accessed. The attack requires high privilege (admin login) and user interaction (viewing the DDNS page), but once injected, the malicious script persists and executes in the browser context of any administrator who views the affected page. No patch information is currently available.

## Affected products

- Netcore NR255-V 1.5.130703

## Timeline

- 2026-09-04: disclosed
- 2026-09-15: advisory

## References

- [https://github.com/draw-ctf/netcore-router-public-refs/blob/main/2026.08.19-netcore-nr255v-ddns-stored-xss.md](https://github.com/draw-ctf/netcore-router-public-refs/blob/main/2026.08.19-netcore-nr255v-ddns-stored-xss.md)
- [https://www.vulncheck.com/advisories/netcore-nr255-v-1.5.130703-stored-cross-site-scripting-via-ddns-eval-in-ddns-wan-list-show-cgi](https://www.vulncheck.com/advisories/netcore-nr255-v-1.5.130703-stored-cross-site-scripting-via-ddns-eval-in-ddns-wan-list-show-cgi)

## 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)
- [Netcore NR255-V out-of-bounds read in filter_arp_put_file.cgi](https://junglewise.ai/threats/cve-2026-92255-netcore-nr255-v-out-of-bounds-read-in-filter-arp-put-file-cgi)
- [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)